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-rw-r--r--doc/Makefile.am23
-rw-r--r--doc/Makefile.in1667
-rw-r--r--doc/diagmeet.note62
-rw-r--r--doc/diffutils.info5313
-rw-r--r--doc/diffutils.texi4759
-rw-r--r--doc/fdl.texi505
-rw-r--r--doc/stamp-vti4
-rw-r--r--doc/version.texi4
8 files changed, 12337 insertions, 0 deletions
diff --git a/doc/Makefile.am b/doc/Makefile.am
new file mode 100644
index 0000000..4f738c6
--- /dev/null
+++ b/doc/Makefile.am
@@ -0,0 +1,23 @@
+# Makefile for GNU diffutils documentation.
+
+# Copyright (C) 2001-2002, 2009-2013, 2015-2016 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+AM_MAKEINFOFLAGS = --no-split
+
+info_TEXINFOS = diffutils.texi
+diffutils_TEXINFOS = fdl.texi
+
+EXTRA_DIST = diagmeet.note
diff --git a/doc/Makefile.in b/doc/Makefile.in
new file mode 100644
index 0000000..23a7fae
--- /dev/null
+++ b/doc/Makefile.in
@@ -0,0 +1,1667 @@
+# Makefile.in generated by automake 1.99a from Makefile.am.
+# @configure_input@
+
+# Copyright (C) 1994-2015 Free Software Foundation, Inc.
+
+# This Makefile.in is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY, to the extent permitted by law; without
+# even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+# PARTICULAR PURPOSE.
+
+@SET_MAKE@
+
+# Makefile for GNU diffutils documentation.
+
+# Copyright (C) 2001-2002, 2009-2013, 2015-2016 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+VPATH = @srcdir@
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+GNULIB_BTOWC = @GNULIB_BTOWC@
+GNULIB_CALLOC_POSIX = @GNULIB_CALLOC_POSIX@
+GNULIB_CANONICALIZE_FILE_NAME = @GNULIB_CANONICALIZE_FILE_NAME@
+GNULIB_CHDIR = @GNULIB_CHDIR@
+GNULIB_CHOWN = @GNULIB_CHOWN@
+GNULIB_CLOSE = @GNULIB_CLOSE@
+GNULIB_CONNECT = @GNULIB_CONNECT@
+GNULIB_DPRINTF = @GNULIB_DPRINTF@
+GNULIB_DUP = @GNULIB_DUP@
+GNULIB_DUP2 = @GNULIB_DUP2@
+GNULIB_DUP3 = @GNULIB_DUP3@
+GNULIB_DUPLOCALE = @GNULIB_DUPLOCALE@
+GNULIB_ENVIRON = @GNULIB_ENVIRON@
+GNULIB_EUIDACCESS = @GNULIB_EUIDACCESS@
+GNULIB_FACCESSAT = @GNULIB_FACCESSAT@
+GNULIB_FCHDIR = @GNULIB_FCHDIR@
+GNULIB_FCHMODAT = @GNULIB_FCHMODAT@
+GNULIB_FCHOWNAT = @GNULIB_FCHOWNAT@
+GNULIB_FCLOSE = @GNULIB_FCLOSE@
+GNULIB_FCNTL = @GNULIB_FCNTL@
+GNULIB_FDATASYNC = @GNULIB_FDATASYNC@
+GNULIB_FDOPEN = @GNULIB_FDOPEN@
+GNULIB_FFLUSH = @GNULIB_FFLUSH@
+GNULIB_FFS = @GNULIB_FFS@
+GNULIB_FFSL = @GNULIB_FFSL@
+GNULIB_FFSLL = @GNULIB_FFSLL@
+GNULIB_FGETC = @GNULIB_FGETC@
+GNULIB_FGETS = @GNULIB_FGETS@
+GNULIB_FOPEN = @GNULIB_FOPEN@
+GNULIB_FPRINTF = @GNULIB_FPRINTF@
+GNULIB_FPRINTF_POSIX = @GNULIB_FPRINTF_POSIX@
+GNULIB_FPURGE = @GNULIB_FPURGE@
+GNULIB_FPUTC = @GNULIB_FPUTC@
+GNULIB_FPUTS = @GNULIB_FPUTS@
+GNULIB_FREAD = @GNULIB_FREAD@
+GNULIB_FREOPEN = @GNULIB_FREOPEN@
+GNULIB_FSCANF = @GNULIB_FSCANF@
+GNULIB_FSEEK = @GNULIB_FSEEK@
+GNULIB_FSEEKO = @GNULIB_FSEEKO@
+GNULIB_FSTAT = @GNULIB_FSTAT@
+GNULIB_FSTATAT = @GNULIB_FSTATAT@
+GNULIB_FSYNC = @GNULIB_FSYNC@
+GNULIB_FTELL = @GNULIB_FTELL@
+GNULIB_FTELLO = @GNULIB_FTELLO@
+GNULIB_FTRUNCATE = @GNULIB_FTRUNCATE@
+GNULIB_FUTIMENS = @GNULIB_FUTIMENS@
+GNULIB_FWRITE = @GNULIB_FWRITE@
+GNULIB_GETC = @GNULIB_GETC@
+GNULIB_GETCHAR = @GNULIB_GETCHAR@
+GNULIB_GETCWD = @GNULIB_GETCWD@
+GNULIB_GETDELIM = @GNULIB_GETDELIM@
+GNULIB_GETDOMAINNAME = @GNULIB_GETDOMAINNAME@
+GNULIB_GETDTABLESIZE = @GNULIB_GETDTABLESIZE@
+GNULIB_GETGROUPS = @GNULIB_GETGROUPS@
+GNULIB_GETHOSTNAME = @GNULIB_GETHOSTNAME@
+GNULIB_GETLINE = @GNULIB_GETLINE@
+GNULIB_GETLOADAVG = @GNULIB_GETLOADAVG@
+GNULIB_GETLOGIN = @GNULIB_GETLOGIN@
+GNULIB_GETLOGIN_R = @GNULIB_GETLOGIN_R@
+GNULIB_GETPAGESIZE = @GNULIB_GETPAGESIZE@
+GNULIB_GETPEERNAME = @GNULIB_GETPEERNAME@
+GNULIB_GETSOCKNAME = @GNULIB_GETSOCKNAME@
+GNULIB_GETSOCKOPT = @GNULIB_GETSOCKOPT@
+GNULIB_GETSUBOPT = @GNULIB_GETSUBOPT@
+GNULIB_GETTIMEOFDAY = @GNULIB_GETTIMEOFDAY@
+GNULIB_GETUSERSHELL = @GNULIB_GETUSERSHELL@
+GNULIB_GL_UNISTD_H_GETOPT = @GNULIB_GL_UNISTD_H_GETOPT@
+GNULIB_GRANTPT = @GNULIB_GRANTPT@
+GNULIB_GROUP_MEMBER = @GNULIB_GROUP_MEMBER@
+GNULIB_ICONV = @GNULIB_ICONV@
+GNULIB_IMAXABS = @GNULIB_IMAXABS@
+GNULIB_IMAXDIV = @GNULIB_IMAXDIV@
+GNULIB_INET_NTOP = @GNULIB_INET_NTOP@
+GNULIB_INET_PTON = @GNULIB_INET_PTON@
+GNULIB_IOCTL = @GNULIB_IOCTL@
+GNULIB_ISATTY = @GNULIB_ISATTY@
+GNULIB_ISBLANK = @GNULIB_ISBLANK@
+GNULIB_ISWBLANK = @GNULIB_ISWBLANK@
+GNULIB_ISWCTYPE = @GNULIB_ISWCTYPE@
+GNULIB_LCHMOD = @GNULIB_LCHMOD@
+GNULIB_LCHOWN = @GNULIB_LCHOWN@
+GNULIB_LINK = @GNULIB_LINK@
+GNULIB_LINKAT = @GNULIB_LINKAT@
+GNULIB_LISTEN = @GNULIB_LISTEN@
+GNULIB_LOCALECONV = @GNULIB_LOCALECONV@
+GNULIB_LSEEK = @GNULIB_LSEEK@
+GNULIB_LSTAT = @GNULIB_LSTAT@
+GNULIB_MALLOC_POSIX = @GNULIB_MALLOC_POSIX@
+GNULIB_MBRLEN = @GNULIB_MBRLEN@
+GNULIB_MBRTOWC = @GNULIB_MBRTOWC@
+GNULIB_MBSCASECMP = @GNULIB_MBSCASECMP@
+GNULIB_MBSCASESTR = @GNULIB_MBSCASESTR@
+GNULIB_MBSCHR = @GNULIB_MBSCHR@
+GNULIB_MBSCSPN = @GNULIB_MBSCSPN@
+GNULIB_MBSINIT = @GNULIB_MBSINIT@
+GNULIB_MBSLEN = @GNULIB_MBSLEN@
+GNULIB_MBSNCASECMP = @GNULIB_MBSNCASECMP@
+GNULIB_MBSNLEN = @GNULIB_MBSNLEN@
+GNULIB_MBSNRTOWCS = @GNULIB_MBSNRTOWCS@
+GNULIB_MBSPBRK = @GNULIB_MBSPBRK@
+GNULIB_MBSPCASECMP = @GNULIB_MBSPCASECMP@
+GNULIB_MBSRCHR = @GNULIB_MBSRCHR@
+GNULIB_MBSRTOWCS = @GNULIB_MBSRTOWCS@
+GNULIB_MBSSEP = @GNULIB_MBSSEP@
+GNULIB_MBSSPN = @GNULIB_MBSSPN@
+GNULIB_MBSSTR = @GNULIB_MBSSTR@
+GNULIB_MBSTOK_R = @GNULIB_MBSTOK_R@
+GNULIB_MBTOWC = @GNULIB_MBTOWC@
+GNULIB_MEMCHR = @GNULIB_MEMCHR@
+GNULIB_MEMMEM = @GNULIB_MEMMEM@
+GNULIB_MEMPCPY = @GNULIB_MEMPCPY@
+GNULIB_MEMRCHR = @GNULIB_MEMRCHR@
+GNULIB_MKDIRAT = @GNULIB_MKDIRAT@
+GNULIB_MKDTEMP = @GNULIB_MKDTEMP@
+GNULIB_MKFIFO = @GNULIB_MKFIFO@
+GNULIB_MKFIFOAT = @GNULIB_MKFIFOAT@
+GNULIB_MKNOD = @GNULIB_MKNOD@
+GNULIB_MKNODAT = @GNULIB_MKNODAT@
+GNULIB_MKOSTEMP = @GNULIB_MKOSTEMP@
+GNULIB_MKOSTEMPS = @GNULIB_MKOSTEMPS@
+GNULIB_MKSTEMP = @GNULIB_MKSTEMP@
+GNULIB_MKSTEMPS = @GNULIB_MKSTEMPS@
+GNULIB_MKTIME = @GNULIB_MKTIME@
+GNULIB_NANOSLEEP = @GNULIB_NANOSLEEP@
+GNULIB_NL_LANGINFO = @GNULIB_NL_LANGINFO@
+GNULIB_NONBLOCKING = @GNULIB_NONBLOCKING@
+GNULIB_OBSTACK_PRINTF = @GNULIB_OBSTACK_PRINTF@
+GNULIB_OBSTACK_PRINTF_POSIX = @GNULIB_OBSTACK_PRINTF_POSIX@
+GNULIB_OPEN = @GNULIB_OPEN@
+GNULIB_OPENAT = @GNULIB_OPENAT@
+GNULIB_PCLOSE = @GNULIB_PCLOSE@
+GNULIB_PERROR = @GNULIB_PERROR@
+GNULIB_PIPE = @GNULIB_PIPE@
+GNULIB_PIPE2 = @GNULIB_PIPE2@
+GNULIB_POPEN = @GNULIB_POPEN@
+GNULIB_POSIX_OPENPT = @GNULIB_POSIX_OPENPT@
+GNULIB_PREAD = @GNULIB_PREAD@
+GNULIB_PRINTF = @GNULIB_PRINTF@
+GNULIB_PRINTF_POSIX = @GNULIB_PRINTF_POSIX@
+GNULIB_PSELECT = @GNULIB_PSELECT@
+GNULIB_PTHREAD_SIGMASK = @GNULIB_PTHREAD_SIGMASK@
+GNULIB_PTSNAME = @GNULIB_PTSNAME@
+GNULIB_PTSNAME_R = @GNULIB_PTSNAME_R@
+GNULIB_PUTC = @GNULIB_PUTC@
+GNULIB_PUTCHAR = @GNULIB_PUTCHAR@
+GNULIB_PUTENV = @GNULIB_PUTENV@
+GNULIB_PUTS = @GNULIB_PUTS@
+GNULIB_PWRITE = @GNULIB_PWRITE@
+GNULIB_QSORT_R = @GNULIB_QSORT_R@
+GNULIB_RAISE = @GNULIB_RAISE@
+GNULIB_RANDOM = @GNULIB_RANDOM@
+GNULIB_RANDOM_R = @GNULIB_RANDOM_R@
+GNULIB_RAWMEMCHR = @GNULIB_RAWMEMCHR@
+GNULIB_READ = @GNULIB_READ@
+GNULIB_READLINK = @GNULIB_READLINK@
+GNULIB_READLINKAT = @GNULIB_READLINKAT@
+GNULIB_REALLOC_POSIX = @GNULIB_REALLOC_POSIX@
+GNULIB_REALPATH = @GNULIB_REALPATH@
+GNULIB_RECV = @GNULIB_RECV@
+GNULIB_RECVFROM = @GNULIB_RECVFROM@
+GNULIB_REMOVE = @GNULIB_REMOVE@
+GNULIB_RENAME = @GNULIB_RENAME@
+GNULIB_RENAMEAT = @GNULIB_RENAMEAT@
+GNULIB_RMDIR = @GNULIB_RMDIR@
+GNULIB_RPMATCH = @GNULIB_RPMATCH@
+GNULIB_SCANF = @GNULIB_SCANF@
+GNULIB_SECURE_GETENV = @GNULIB_SECURE_GETENV@
+GNULIB_SELECT = @GNULIB_SELECT@
+GNULIB_SEND = @GNULIB_SEND@
+GNULIB_SENDTO = @GNULIB_SENDTO@
+GNULIB_SETENV = @GNULIB_SETENV@
+GNULIB_SETHOSTNAME = @GNULIB_SETHOSTNAME@
+GNULIB_SETLOCALE = @GNULIB_SETLOCALE@
+GNULIB_SETSOCKOPT = @GNULIB_SETSOCKOPT@
+GNULIB_SHUTDOWN = @GNULIB_SHUTDOWN@
+GNULIB_SIGACTION = @GNULIB_SIGACTION@
+GNULIB_SIGNAL_H_SIGPIPE = @GNULIB_SIGNAL_H_SIGPIPE@
+GNULIB_SIGPROCMASK = @GNULIB_SIGPROCMASK@
+GNULIB_SLEEP = @GNULIB_SLEEP@
+GNULIB_SNPRINTF = @GNULIB_SNPRINTF@
+GNULIB_SOCKET = @GNULIB_SOCKET@
+GNULIB_SPRINTF_POSIX = @GNULIB_SPRINTF_POSIX@
+GNULIB_STAT = @GNULIB_STAT@
+GNULIB_STDIO_H_NONBLOCKING = @GNULIB_STDIO_H_NONBLOCKING@
+GNULIB_STDIO_H_SIGPIPE = @GNULIB_STDIO_H_SIGPIPE@
+GNULIB_STPCPY = @GNULIB_STPCPY@
+GNULIB_STPNCPY = @GNULIB_STPNCPY@
+GNULIB_STRCASESTR = @GNULIB_STRCASESTR@
+GNULIB_STRCHRNUL = @GNULIB_STRCHRNUL@
+GNULIB_STRDUP = @GNULIB_STRDUP@
+GNULIB_STRERROR = @GNULIB_STRERROR@
+GNULIB_STRERROR_R = @GNULIB_STRERROR_R@
+GNULIB_STRNCAT = @GNULIB_STRNCAT@
+GNULIB_STRNDUP = @GNULIB_STRNDUP@
+GNULIB_STRNLEN = @GNULIB_STRNLEN@
+GNULIB_STRPBRK = @GNULIB_STRPBRK@
+GNULIB_STRPTIME = @GNULIB_STRPTIME@
+GNULIB_STRSEP = @GNULIB_STRSEP@
+GNULIB_STRSIGNAL = @GNULIB_STRSIGNAL@
+GNULIB_STRSTR = @GNULIB_STRSTR@
+GNULIB_STRTOD = @GNULIB_STRTOD@
+GNULIB_STRTOIMAX = @GNULIB_STRTOIMAX@
+GNULIB_STRTOK_R = @GNULIB_STRTOK_R@
+GNULIB_STRTOLL = @GNULIB_STRTOLL@
+GNULIB_STRTOULL = @GNULIB_STRTOULL@
+GNULIB_STRTOUMAX = @GNULIB_STRTOUMAX@
+GNULIB_STRVERSCMP = @GNULIB_STRVERSCMP@
+GNULIB_SYMLINK = @GNULIB_SYMLINK@
+GNULIB_SYMLINKAT = @GNULIB_SYMLINKAT@
+GNULIB_SYSTEM_POSIX = @GNULIB_SYSTEM_POSIX@
+GNULIB_TIMEGM = @GNULIB_TIMEGM@
+GNULIB_TIME_R = @GNULIB_TIME_R@
+GNULIB_TIME_RZ = @GNULIB_TIME_RZ@
+GNULIB_TMPFILE = @GNULIB_TMPFILE@
+GNULIB_TOWCTRANS = @GNULIB_TOWCTRANS@
+GNULIB_TTYNAME_R = @GNULIB_TTYNAME_R@
+GNULIB_UNISTD_H_NONBLOCKING = @GNULIB_UNISTD_H_NONBLOCKING@
+GNULIB_UNISTD_H_SIGPIPE = @GNULIB_UNISTD_H_SIGPIPE@
+GNULIB_UNLINK = @GNULIB_UNLINK@
+GNULIB_UNLINKAT = @GNULIB_UNLINKAT@
+GNULIB_UNLOCKPT = @GNULIB_UNLOCKPT@
+GNULIB_UNSETENV = @GNULIB_UNSETENV@
+GNULIB_USLEEP = @GNULIB_USLEEP@
+GNULIB_UTIMENSAT = @GNULIB_UTIMENSAT@
+GNULIB_VASPRINTF = @GNULIB_VASPRINTF@
+GNULIB_VDPRINTF = @GNULIB_VDPRINTF@
+GNULIB_VFPRINTF = @GNULIB_VFPRINTF@
+GNULIB_VFPRINTF_POSIX = @GNULIB_VFPRINTF_POSIX@
+GNULIB_VFSCANF = @GNULIB_VFSCANF@
+GNULIB_VPRINTF = @GNULIB_VPRINTF@
+GNULIB_VPRINTF_POSIX = @GNULIB_VPRINTF_POSIX@
+GNULIB_VSCANF = @GNULIB_VSCANF@
+GNULIB_VSNPRINTF = @GNULIB_VSNPRINTF@
+GNULIB_VSPRINTF_POSIX = @GNULIB_VSPRINTF_POSIX@
+GNULIB_WAITPID = @GNULIB_WAITPID@
+GNULIB_WARN_CFLAGS = @GNULIB_WARN_CFLAGS@
+GNULIB_WCPCPY = @GNULIB_WCPCPY@
+GNULIB_WCPNCPY = @GNULIB_WCPNCPY@
+GNULIB_WCRTOMB = @GNULIB_WCRTOMB@
+GNULIB_WCSCASECMP = @GNULIB_WCSCASECMP@
+GNULIB_WCSCAT = @GNULIB_WCSCAT@
+GNULIB_WCSCHR = @GNULIB_WCSCHR@
+GNULIB_WCSCMP = @GNULIB_WCSCMP@
+GNULIB_WCSCOLL = @GNULIB_WCSCOLL@
+GNULIB_WCSCPY = @GNULIB_WCSCPY@
+GNULIB_WCSCSPN = @GNULIB_WCSCSPN@
+GNULIB_WCSDUP = @GNULIB_WCSDUP@
+GNULIB_WCSLEN = @GNULIB_WCSLEN@
+GNULIB_WCSNCASECMP = @GNULIB_WCSNCASECMP@
+GNULIB_WCSNCAT = @GNULIB_WCSNCAT@
+GNULIB_WCSNCMP = @GNULIB_WCSNCMP@
+GNULIB_WCSNCPY = @GNULIB_WCSNCPY@
+GNULIB_WCSNLEN = @GNULIB_WCSNLEN@
+GNULIB_WCSNRTOMBS = @GNULIB_WCSNRTOMBS@
+GNULIB_WCSPBRK = @GNULIB_WCSPBRK@
+GNULIB_WCSRCHR = @GNULIB_WCSRCHR@
+GNULIB_WCSRTOMBS = @GNULIB_WCSRTOMBS@
+GNULIB_WCSSPN = @GNULIB_WCSSPN@
+GNULIB_WCSSTR = @GNULIB_WCSSTR@
+GNULIB_WCSTOK = @GNULIB_WCSTOK@
+GNULIB_WCSWIDTH = @GNULIB_WCSWIDTH@
+GNULIB_WCSXFRM = @GNULIB_WCSXFRM@
+GNULIB_WCTOB = @GNULIB_WCTOB@
+GNULIB_WCTOMB = @GNULIB_WCTOMB@
+GNULIB_WCTRANS = @GNULIB_WCTRANS@
+GNULIB_WCTYPE = @GNULIB_WCTYPE@
+GNULIB_WCWIDTH = @GNULIB_WCWIDTH@
+GNULIB_WMEMCHR = @GNULIB_WMEMCHR@
+GNULIB_WMEMCMP = @GNULIB_WMEMCMP@
+GNULIB_WMEMCPY = @GNULIB_WMEMCPY@
+GNULIB_WMEMMOVE = @GNULIB_WMEMMOVE@
+GNULIB_WMEMSET = @GNULIB_WMEMSET@
+GNULIB_WRITE = @GNULIB_WRITE@
+GNULIB__EXIT = @GNULIB__EXIT@
+GREP = @GREP@
+HAVE_ACCEPT4 = @HAVE_ACCEPT4@
+HAVE_ARPA_INET_H = @HAVE_ARPA_INET_H@
+HAVE_ATOLL = @HAVE_ATOLL@
+HAVE_BTOWC = @HAVE_BTOWC@
+HAVE_CANONICALIZE_FILE_NAME = @HAVE_CANONICALIZE_FILE_NAME@
+HAVE_CHOWN = @HAVE_CHOWN@
+HAVE_DECL_ENVIRON = @HAVE_DECL_ENVIRON@
+HAVE_DECL_FCHDIR = @HAVE_DECL_FCHDIR@
+HAVE_DECL_FDATASYNC = @HAVE_DECL_FDATASYNC@
+HAVE_DECL_FPURGE = @HAVE_DECL_FPURGE@
+HAVE_DECL_FSEEKO = @HAVE_DECL_FSEEKO@
+HAVE_DECL_FTELLO = @HAVE_DECL_FTELLO@
+HAVE_DECL_GETDELIM = @HAVE_DECL_GETDELIM@
+HAVE_DECL_GETDOMAINNAME = @HAVE_DECL_GETDOMAINNAME@
+HAVE_DECL_GETLINE = @HAVE_DECL_GETLINE@
+HAVE_DECL_GETLOADAVG = @HAVE_DECL_GETLOADAVG@
+HAVE_DECL_GETLOGIN_R = @HAVE_DECL_GETLOGIN_R@
+HAVE_DECL_GETPAGESIZE = @HAVE_DECL_GETPAGESIZE@
+HAVE_DECL_GETUSERSHELL = @HAVE_DECL_GETUSERSHELL@
+HAVE_DECL_IMAXABS = @HAVE_DECL_IMAXABS@
+HAVE_DECL_IMAXDIV = @HAVE_DECL_IMAXDIV@
+HAVE_DECL_INET_NTOP = @HAVE_DECL_INET_NTOP@
+HAVE_DECL_INET_PTON = @HAVE_DECL_INET_PTON@
+HAVE_DECL_LOCALTIME_R = @HAVE_DECL_LOCALTIME_R@
+HAVE_DECL_MEMMEM = @HAVE_DECL_MEMMEM@
+HAVE_DECL_MEMRCHR = @HAVE_DECL_MEMRCHR@
+HAVE_DECL_OBSTACK_PRINTF = @HAVE_DECL_OBSTACK_PRINTF@
+HAVE_DECL_SETENV = @HAVE_DECL_SETENV@
+HAVE_DECL_SETHOSTNAME = @HAVE_DECL_SETHOSTNAME@
+HAVE_DECL_SNPRINTF = @HAVE_DECL_SNPRINTF@
+HAVE_DECL_STRDUP = @HAVE_DECL_STRDUP@
+HAVE_DECL_STRERROR_R = @HAVE_DECL_STRERROR_R@
+HAVE_DECL_STRNCASECMP = @HAVE_DECL_STRNCASECMP@
+HAVE_DECL_STRNDUP = @HAVE_DECL_STRNDUP@
+HAVE_DECL_STRNLEN = @HAVE_DECL_STRNLEN@
+HAVE_DECL_STRSIGNAL = @HAVE_DECL_STRSIGNAL@
+HAVE_DECL_STRTOIMAX = @HAVE_DECL_STRTOIMAX@
+HAVE_DECL_STRTOK_R = @HAVE_DECL_STRTOK_R@
+HAVE_DECL_STRTOUMAX = @HAVE_DECL_STRTOUMAX@
+HAVE_DECL_TTYNAME_R = @HAVE_DECL_TTYNAME_R@
+HAVE_DECL_UNSETENV = @HAVE_DECL_UNSETENV@
+HAVE_DECL_VSNPRINTF = @HAVE_DECL_VSNPRINTF@
+HAVE_DECL_WCTOB = @HAVE_DECL_WCTOB@
+HAVE_DECL_WCWIDTH = @HAVE_DECL_WCWIDTH@
+HAVE_DPRINTF = @HAVE_DPRINTF@
+HAVE_DUP2 = @HAVE_DUP2@
+HAVE_DUP3 = @HAVE_DUP3@
+HAVE_DUPLOCALE = @HAVE_DUPLOCALE@
+HAVE_EUIDACCESS = @HAVE_EUIDACCESS@
+HAVE_FACCESSAT = @HAVE_FACCESSAT@
+HAVE_FCHDIR = @HAVE_FCHDIR@
+HAVE_FCHMODAT = @HAVE_FCHMODAT@
+HAVE_FCHOWNAT = @HAVE_FCHOWNAT@
+HAVE_FCNTL = @HAVE_FCNTL@
+HAVE_FDATASYNC = @HAVE_FDATASYNC@
+HAVE_FEATURES_H = @HAVE_FEATURES_H@
+HAVE_FFS = @HAVE_FFS@
+HAVE_FFSL = @HAVE_FFSL@
+HAVE_FFSLL = @HAVE_FFSLL@
+HAVE_FSEEKO = @HAVE_FSEEKO@
+HAVE_FSTATAT = @HAVE_FSTATAT@
+HAVE_FSYNC = @HAVE_FSYNC@
+HAVE_FTELLO = @HAVE_FTELLO@
+HAVE_FTRUNCATE = @HAVE_FTRUNCATE@
+HAVE_FUTIMENS = @HAVE_FUTIMENS@
+HAVE_GETDTABLESIZE = @HAVE_GETDTABLESIZE@
+HAVE_GETGROUPS = @HAVE_GETGROUPS@
+HAVE_GETHOSTNAME = @HAVE_GETHOSTNAME@
+HAVE_GETLOGIN = @HAVE_GETLOGIN@
+HAVE_GETOPT_H = @HAVE_GETOPT_H@
+HAVE_GETPAGESIZE = @HAVE_GETPAGESIZE@
+HAVE_GETSUBOPT = @HAVE_GETSUBOPT@
+HAVE_GETTIMEOFDAY = @HAVE_GETTIMEOFDAY@
+HAVE_GRANTPT = @HAVE_GRANTPT@
+HAVE_GROUP_MEMBER = @HAVE_GROUP_MEMBER@
+HAVE_INTTYPES_H = @HAVE_INTTYPES_H@
+HAVE_ISBLANK = @HAVE_ISBLANK@
+HAVE_ISWBLANK = @HAVE_ISWBLANK@
+HAVE_ISWCNTRL = @HAVE_ISWCNTRL@
+HAVE_LANGINFO_CODESET = @HAVE_LANGINFO_CODESET@
+HAVE_LANGINFO_ERA = @HAVE_LANGINFO_ERA@
+HAVE_LANGINFO_H = @HAVE_LANGINFO_H@
+HAVE_LANGINFO_T_FMT_AMPM = @HAVE_LANGINFO_T_FMT_AMPM@
+HAVE_LANGINFO_YESEXPR = @HAVE_LANGINFO_YESEXPR@
+HAVE_LCHMOD = @HAVE_LCHMOD@
+HAVE_LCHOWN = @HAVE_LCHOWN@
+HAVE_LIBSIGSEGV = @HAVE_LIBSIGSEGV@
+HAVE_LINK = @HAVE_LINK@
+HAVE_LINKAT = @HAVE_LINKAT@
+HAVE_LONG_LONG_INT = @HAVE_LONG_LONG_INT@
+HAVE_LSTAT = @HAVE_LSTAT@
+HAVE_MAX_ALIGN_T = @HAVE_MAX_ALIGN_T@
+HAVE_MBRLEN = @HAVE_MBRLEN@
+HAVE_MBRTOWC = @HAVE_MBRTOWC@
+HAVE_MBSINIT = @HAVE_MBSINIT@
+HAVE_MBSLEN = @HAVE_MBSLEN@
+HAVE_MBSNRTOWCS = @HAVE_MBSNRTOWCS@
+HAVE_MBSRTOWCS = @HAVE_MBSRTOWCS@
+HAVE_MEMCHR = @HAVE_MEMCHR@
+HAVE_MEMPCPY = @HAVE_MEMPCPY@
+HAVE_MKDIRAT = @HAVE_MKDIRAT@
+HAVE_MKDTEMP = @HAVE_MKDTEMP@
+HAVE_MKFIFO = @HAVE_MKFIFO@
+HAVE_MKFIFOAT = @HAVE_MKFIFOAT@
+HAVE_MKNOD = @HAVE_MKNOD@
+HAVE_MKNODAT = @HAVE_MKNODAT@
+HAVE_MKOSTEMP = @HAVE_MKOSTEMP@
+HAVE_MKOSTEMPS = @HAVE_MKOSTEMPS@
+HAVE_MKSTEMP = @HAVE_MKSTEMP@
+HAVE_MKSTEMPS = @HAVE_MKSTEMPS@
+HAVE_MSVC_INVALID_PARAMETER_HANDLER = @HAVE_MSVC_INVALID_PARAMETER_HANDLER@
+HAVE_NANOSLEEP = @HAVE_NANOSLEEP@
+HAVE_NETINET_IN_H = @HAVE_NETINET_IN_H@
+HAVE_NL_LANGINFO = @HAVE_NL_LANGINFO@
+HAVE_OPENAT = @HAVE_OPENAT@
+HAVE_OS_H = @HAVE_OS_H@
+HAVE_PCLOSE = @HAVE_PCLOSE@
+HAVE_PIPE = @HAVE_PIPE@
+HAVE_PIPE2 = @HAVE_PIPE2@
+HAVE_POPEN = @HAVE_POPEN@
+HAVE_POSIX_OPENPT = @HAVE_POSIX_OPENPT@
+HAVE_POSIX_SIGNALBLOCKING = @HAVE_POSIX_SIGNALBLOCKING@
+HAVE_PREAD = @HAVE_PREAD@
+HAVE_PSELECT = @HAVE_PSELECT@
+HAVE_PTHREAD_SIGMASK = @HAVE_PTHREAD_SIGMASK@
+HAVE_PTSNAME = @HAVE_PTSNAME@
+HAVE_PTSNAME_R = @HAVE_PTSNAME_R@
+HAVE_PWRITE = @HAVE_PWRITE@
+HAVE_RAISE = @HAVE_RAISE@
+HAVE_RANDOM = @HAVE_RANDOM@
+HAVE_RANDOM_H = @HAVE_RANDOM_H@
+HAVE_RANDOM_R = @HAVE_RANDOM_R@
+HAVE_RAWMEMCHR = @HAVE_RAWMEMCHR@
+HAVE_READLINK = @HAVE_READLINK@
+HAVE_READLINKAT = @HAVE_READLINKAT@
+HAVE_REALPATH = @HAVE_REALPATH@
+HAVE_RENAMEAT = @HAVE_RENAMEAT@
+HAVE_RPMATCH = @HAVE_RPMATCH@
+HAVE_SA_FAMILY_T = @HAVE_SA_FAMILY_T@
+HAVE_SECURE_GETENV = @HAVE_SECURE_GETENV@
+HAVE_SETENV = @HAVE_SETENV@
+HAVE_SETHOSTNAME = @HAVE_SETHOSTNAME@
+HAVE_SIGACTION = @HAVE_SIGACTION@
+HAVE_SIGHANDLER_T = @HAVE_SIGHANDLER_T@
+HAVE_SIGINFO_T = @HAVE_SIGINFO_T@
+HAVE_SIGNED_SIG_ATOMIC_T = @HAVE_SIGNED_SIG_ATOMIC_T@
+HAVE_SIGNED_WCHAR_T = @HAVE_SIGNED_WCHAR_T@
+HAVE_SIGNED_WINT_T = @HAVE_SIGNED_WINT_T@
+HAVE_SIGSET_T = @HAVE_SIGSET_T@
+HAVE_SLEEP = @HAVE_SLEEP@
+HAVE_STDINT_H = @HAVE_STDINT_H@
+HAVE_STPCPY = @HAVE_STPCPY@
+HAVE_STPNCPY = @HAVE_STPNCPY@
+HAVE_STRCASECMP = @HAVE_STRCASECMP@
+HAVE_STRCASESTR = @HAVE_STRCASESTR@
+HAVE_STRCHRNUL = @HAVE_STRCHRNUL@
+HAVE_STRINGS_H = @HAVE_STRINGS_H@
+HAVE_STRPBRK = @HAVE_STRPBRK@
+HAVE_STRPTIME = @HAVE_STRPTIME@
+HAVE_STRSEP = @HAVE_STRSEP@
+HAVE_STRTOD = @HAVE_STRTOD@
+HAVE_STRTOLL = @HAVE_STRTOLL@
+HAVE_STRTOULL = @HAVE_STRTOULL@
+HAVE_STRUCT_RANDOM_DATA = @HAVE_STRUCT_RANDOM_DATA@
+HAVE_STRUCT_SIGACTION_SA_SIGACTION = @HAVE_STRUCT_SIGACTION_SA_SIGACTION@
+HAVE_STRUCT_SOCKADDR_STORAGE = @HAVE_STRUCT_SOCKADDR_STORAGE@
+HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY = @HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY@
+HAVE_STRUCT_TIMEVAL = @HAVE_STRUCT_TIMEVAL@
+HAVE_STRVERSCMP = @HAVE_STRVERSCMP@
+HAVE_SYMLINK = @HAVE_SYMLINK@
+HAVE_SYMLINKAT = @HAVE_SYMLINKAT@
+HAVE_SYS_BITYPES_H = @HAVE_SYS_BITYPES_H@
+HAVE_SYS_INTTYPES_H = @HAVE_SYS_INTTYPES_H@
+HAVE_SYS_IOCTL_H = @HAVE_SYS_IOCTL_H@
+HAVE_SYS_LOADAVG_H = @HAVE_SYS_LOADAVG_H@
+HAVE_SYS_PARAM_H = @HAVE_SYS_PARAM_H@
+HAVE_SYS_SELECT_H = @HAVE_SYS_SELECT_H@
+HAVE_SYS_SOCKET_H = @HAVE_SYS_SOCKET_H@
+HAVE_SYS_TIME_H = @HAVE_SYS_TIME_H@
+HAVE_SYS_TYPES_H = @HAVE_SYS_TYPES_H@
+HAVE_SYS_UIO_H = @HAVE_SYS_UIO_H@
+HAVE_TIMEGM = @HAVE_TIMEGM@
+HAVE_TIMEZONE_T = @HAVE_TIMEZONE_T@
+HAVE_TYPE_VOLATILE_SIG_ATOMIC_T = @HAVE_TYPE_VOLATILE_SIG_ATOMIC_T@
+HAVE_UNISTD_H = @HAVE_UNISTD_H@
+HAVE_UNLINKAT = @HAVE_UNLINKAT@
+HAVE_UNLOCKPT = @HAVE_UNLOCKPT@
+HAVE_UNSIGNED_LONG_LONG_INT = @HAVE_UNSIGNED_LONG_LONG_INT@
+HAVE_USLEEP = @HAVE_USLEEP@
+HAVE_UTIMENSAT = @HAVE_UTIMENSAT@
+HAVE_VASPRINTF = @HAVE_VASPRINTF@
+HAVE_VDPRINTF = @HAVE_VDPRINTF@
+HAVE_WCHAR_H = @HAVE_WCHAR_H@
+HAVE_WCHAR_T = @HAVE_WCHAR_T@
+HAVE_WCPCPY = @HAVE_WCPCPY@
+HAVE_WCPNCPY = @HAVE_WCPNCPY@
+HAVE_WCRTOMB = @HAVE_WCRTOMB@
+HAVE_WCSCASECMP = @HAVE_WCSCASECMP@
+HAVE_WCSCAT = @HAVE_WCSCAT@
+HAVE_WCSCHR = @HAVE_WCSCHR@
+HAVE_WCSCMP = @HAVE_WCSCMP@
+HAVE_WCSCOLL = @HAVE_WCSCOLL@
+HAVE_WCSCPY = @HAVE_WCSCPY@
+HAVE_WCSCSPN = @HAVE_WCSCSPN@
+HAVE_WCSDUP = @HAVE_WCSDUP@
+HAVE_WCSLEN = @HAVE_WCSLEN@
+HAVE_WCSNCASECMP = @HAVE_WCSNCASECMP@
+HAVE_WCSNCAT = @HAVE_WCSNCAT@
+HAVE_WCSNCMP = @HAVE_WCSNCMP@
+HAVE_WCSNCPY = @HAVE_WCSNCPY@
+HAVE_WCSNLEN = @HAVE_WCSNLEN@
+HAVE_WCSNRTOMBS = @HAVE_WCSNRTOMBS@
+HAVE_WCSPBRK = @HAVE_WCSPBRK@
+HAVE_WCSRCHR = @HAVE_WCSRCHR@
+HAVE_WCSRTOMBS = @HAVE_WCSRTOMBS@
+HAVE_WCSSPN = @HAVE_WCSSPN@
+HAVE_WCSSTR = @HAVE_WCSSTR@
+HAVE_WCSTOK = @HAVE_WCSTOK@
+HAVE_WCSWIDTH = @HAVE_WCSWIDTH@
+HAVE_WCSXFRM = @HAVE_WCSXFRM@
+HAVE_WCTRANS_T = @HAVE_WCTRANS_T@
+HAVE_WCTYPE_H = @HAVE_WCTYPE_H@
+HAVE_WCTYPE_T = @HAVE_WCTYPE_T@
+HAVE_WINSOCK2_H = @HAVE_WINSOCK2_H@
+HAVE_WINT_T = @HAVE_WINT_T@
+HAVE_WMEMCHR = @HAVE_WMEMCHR@
+HAVE_WMEMCMP = @HAVE_WMEMCMP@
+HAVE_WMEMCPY = @HAVE_WMEMCPY@
+HAVE_WMEMMOVE = @HAVE_WMEMMOVE@
+HAVE_WMEMSET = @HAVE_WMEMSET@
+HAVE_WS2TCPIP_H = @HAVE_WS2TCPIP_H@
+HAVE_XLOCALE_H = @HAVE_XLOCALE_H@
+HAVE__BOOL = @HAVE__BOOL@
+HAVE__EXIT = @HAVE__EXIT@
+HELP2MAN = @HELP2MAN@
+ICONV_CONST = @ICONV_CONST@
+ICONV_H = @ICONV_H@
+INCLUDE_NEXT = @INCLUDE_NEXT@
+INCLUDE_NEXT_AS_FIRST_DIRECTIVE = @INCLUDE_NEXT_AS_FIRST_DIRECTIVE@
+INET_PTON_LIB = @INET_PTON_LIB@
+INSTALL = @INSTALL@
+INSTALL_DATA = @INSTALL_DATA@
+INSTALL_PROGRAM = @INSTALL_PROGRAM@
+INSTALL_SCRIPT = @INSTALL_SCRIPT@
+INSTALL_STRIP_PROGRAM = @INSTALL_STRIP_PROGRAM@
+INT32_MAX_LT_INTMAX_MAX = @INT32_MAX_LT_INTMAX_MAX@
+INT64_MAX_EQ_LONG_MAX = @INT64_MAX_EQ_LONG_MAX@
+INTLLIBS = @INTLLIBS@
+INTL_MACOSX_LIBS = @INTL_MACOSX_LIBS@
+LDFLAGS = @LDFLAGS@
+LIBCSTACK = @LIBCSTACK@
+LIBDIFFUTILS_LIBDEPS = @LIBDIFFUTILS_LIBDEPS@
+LIBDIFFUTILS_LTLIBDEPS = @LIBDIFFUTILS_LTLIBDEPS@
+LIBICONV = @LIBICONV@
+LIBINTL = @LIBINTL@
+LIBOBJS = @LIBOBJS@
+LIBS = @LIBS@
+LIBSIGSEGV = @LIBSIGSEGV@
+LIBSIGSEGV_PREFIX = @LIBSIGSEGV_PREFIX@
+LIBSOCKET = @LIBSOCKET@
+LIBTESTS_LIBDEPS = @LIBTESTS_LIBDEPS@
+LIBUNISTRING_UNISTR_H = @LIBUNISTRING_UNISTR_H@
+LIBUNISTRING_UNITYPES_H = @LIBUNISTRING_UNITYPES_H@
+LIBUNISTRING_UNIWIDTH_H = @LIBUNISTRING_UNIWIDTH_H@
+LIB_CLOCK_GETTIME = @LIB_CLOCK_GETTIME@
+LIB_NANOSLEEP = @LIB_NANOSLEEP@
+LIB_SELECT = @LIB_SELECT@
+LOCALCHARSET_TESTS_ENVIRONMENT = @LOCALCHARSET_TESTS_ENVIRONMENT@
+LOCALE_FR = @LOCALE_FR@
+LOCALE_FR_UTF8 = @LOCALE_FR_UTF8@
+LOCALE_JA = @LOCALE_JA@
+LOCALE_TR_UTF8 = @LOCALE_TR_UTF8@
+LOCALE_ZH_CN = @LOCALE_ZH_CN@
+LTLIBCSTACK = @LTLIBCSTACK@
+LTLIBICONV = @LTLIBICONV@
+LTLIBINTL = @LTLIBINTL@
+LTLIBOBJS = @LTLIBOBJS@
+LTLIBSIGSEGV = @LTLIBSIGSEGV@
+MAKEINFO = @MAKEINFO@
+MKDIR_P = @MKDIR_P@
+MSGFMT = @MSGFMT@
+MSGFMT_015 = @MSGFMT_015@
+MSGMERGE = @MSGMERGE@
+NETINET_IN_H = @NETINET_IN_H@
+NEXT_ARPA_INET_H = @NEXT_ARPA_INET_H@
+NEXT_AS_FIRST_DIRECTIVE_ARPA_INET_H = @NEXT_AS_FIRST_DIRECTIVE_ARPA_INET_H@
+NEXT_AS_FIRST_DIRECTIVE_CTYPE_H = @NEXT_AS_FIRST_DIRECTIVE_CTYPE_H@
+NEXT_AS_FIRST_DIRECTIVE_ERRNO_H = @NEXT_AS_FIRST_DIRECTIVE_ERRNO_H@
+NEXT_AS_FIRST_DIRECTIVE_FCNTL_H = @NEXT_AS_FIRST_DIRECTIVE_FCNTL_H@
+NEXT_AS_FIRST_DIRECTIVE_FLOAT_H = @NEXT_AS_FIRST_DIRECTIVE_FLOAT_H@
+NEXT_AS_FIRST_DIRECTIVE_GETOPT_H = @NEXT_AS_FIRST_DIRECTIVE_GETOPT_H@
+NEXT_AS_FIRST_DIRECTIVE_ICONV_H = @NEXT_AS_FIRST_DIRECTIVE_ICONV_H@
+NEXT_AS_FIRST_DIRECTIVE_INTTYPES_H = @NEXT_AS_FIRST_DIRECTIVE_INTTYPES_H@
+NEXT_AS_FIRST_DIRECTIVE_LANGINFO_H = @NEXT_AS_FIRST_DIRECTIVE_LANGINFO_H@
+NEXT_AS_FIRST_DIRECTIVE_LOCALE_H = @NEXT_AS_FIRST_DIRECTIVE_LOCALE_H@
+NEXT_AS_FIRST_DIRECTIVE_NETINET_IN_H = @NEXT_AS_FIRST_DIRECTIVE_NETINET_IN_H@
+NEXT_AS_FIRST_DIRECTIVE_SIGNAL_H = @NEXT_AS_FIRST_DIRECTIVE_SIGNAL_H@
+NEXT_AS_FIRST_DIRECTIVE_STDARG_H = @NEXT_AS_FIRST_DIRECTIVE_STDARG_H@
+NEXT_AS_FIRST_DIRECTIVE_STDDEF_H = @NEXT_AS_FIRST_DIRECTIVE_STDDEF_H@
+NEXT_AS_FIRST_DIRECTIVE_STDINT_H = @NEXT_AS_FIRST_DIRECTIVE_STDINT_H@
+NEXT_AS_FIRST_DIRECTIVE_STDIO_H = @NEXT_AS_FIRST_DIRECTIVE_STDIO_H@
+NEXT_AS_FIRST_DIRECTIVE_STDLIB_H = @NEXT_AS_FIRST_DIRECTIVE_STDLIB_H@
+NEXT_AS_FIRST_DIRECTIVE_STRINGS_H = @NEXT_AS_FIRST_DIRECTIVE_STRINGS_H@
+NEXT_AS_FIRST_DIRECTIVE_STRING_H = @NEXT_AS_FIRST_DIRECTIVE_STRING_H@
+NEXT_AS_FIRST_DIRECTIVE_SYS_IOCTL_H = @NEXT_AS_FIRST_DIRECTIVE_SYS_IOCTL_H@
+NEXT_AS_FIRST_DIRECTIVE_SYS_SELECT_H = @NEXT_AS_FIRST_DIRECTIVE_SYS_SELECT_H@
+NEXT_AS_FIRST_DIRECTIVE_SYS_SOCKET_H = @NEXT_AS_FIRST_DIRECTIVE_SYS_SOCKET_H@
+NEXT_AS_FIRST_DIRECTIVE_SYS_STAT_H = @NEXT_AS_FIRST_DIRECTIVE_SYS_STAT_H@
+NEXT_AS_FIRST_DIRECTIVE_SYS_TIME_H = @NEXT_AS_FIRST_DIRECTIVE_SYS_TIME_H@
+NEXT_AS_FIRST_DIRECTIVE_SYS_TYPES_H = @NEXT_AS_FIRST_DIRECTIVE_SYS_TYPES_H@
+NEXT_AS_FIRST_DIRECTIVE_SYS_UIO_H = @NEXT_AS_FIRST_DIRECTIVE_SYS_UIO_H@
+NEXT_AS_FIRST_DIRECTIVE_SYS_WAIT_H = @NEXT_AS_FIRST_DIRECTIVE_SYS_WAIT_H@
+NEXT_AS_FIRST_DIRECTIVE_TIME_H = @NEXT_AS_FIRST_DIRECTIVE_TIME_H@
+NEXT_AS_FIRST_DIRECTIVE_UNISTD_H = @NEXT_AS_FIRST_DIRECTIVE_UNISTD_H@
+NEXT_AS_FIRST_DIRECTIVE_WCHAR_H = @NEXT_AS_FIRST_DIRECTIVE_WCHAR_H@
+NEXT_AS_FIRST_DIRECTIVE_WCTYPE_H = @NEXT_AS_FIRST_DIRECTIVE_WCTYPE_H@
+NEXT_CTYPE_H = @NEXT_CTYPE_H@
+NEXT_ERRNO_H = @NEXT_ERRNO_H@
+NEXT_FCNTL_H = @NEXT_FCNTL_H@
+NEXT_FLOAT_H = @NEXT_FLOAT_H@
+NEXT_GETOPT_H = @NEXT_GETOPT_H@
+NEXT_ICONV_H = @NEXT_ICONV_H@
+NEXT_INTTYPES_H = @NEXT_INTTYPES_H@
+NEXT_LANGINFO_H = @NEXT_LANGINFO_H@
+NEXT_LOCALE_H = @NEXT_LOCALE_H@
+NEXT_NETINET_IN_H = @NEXT_NETINET_IN_H@
+NEXT_SIGNAL_H = @NEXT_SIGNAL_H@
+NEXT_STDARG_H = @NEXT_STDARG_H@
+NEXT_STDDEF_H = @NEXT_STDDEF_H@
+NEXT_STDINT_H = @NEXT_STDINT_H@
+NEXT_STDIO_H = @NEXT_STDIO_H@
+NEXT_STDLIB_H = @NEXT_STDLIB_H@
+NEXT_STRINGS_H = @NEXT_STRINGS_H@
+NEXT_STRING_H = @NEXT_STRING_H@
+NEXT_SYS_IOCTL_H = @NEXT_SYS_IOCTL_H@
+NEXT_SYS_SELECT_H = @NEXT_SYS_SELECT_H@
+NEXT_SYS_SOCKET_H = @NEXT_SYS_SOCKET_H@
+NEXT_SYS_STAT_H = @NEXT_SYS_STAT_H@
+NEXT_SYS_TIME_H = @NEXT_SYS_TIME_H@
+NEXT_SYS_TYPES_H = @NEXT_SYS_TYPES_H@
+NEXT_SYS_UIO_H = @NEXT_SYS_UIO_H@
+NEXT_SYS_WAIT_H = @NEXT_SYS_WAIT_H@
+NEXT_TIME_H = @NEXT_TIME_H@
+NEXT_UNISTD_H = @NEXT_UNISTD_H@
+NEXT_WCHAR_H = @NEXT_WCHAR_H@
+NEXT_WCTYPE_H = @NEXT_WCTYPE_H@
+OBJEXT = @OBJEXT@
+PACKAGE = @PACKAGE@
+PACKAGE_BUGREPORT = @PACKAGE_BUGREPORT@
+PACKAGE_NAME = @PACKAGE_NAME@
+PACKAGE_STRING = @PACKAGE_STRING@
+PACKAGE_TARNAME = @PACKAGE_TARNAME@
+PACKAGE_URL = @PACKAGE_URL@
+PACKAGE_VERSION = @PACKAGE_VERSION@
+PATH_SEPARATOR = @PATH_SEPARATOR@
+POSUB = @POSUB@
+PRAGMA_COLUMNS = @PRAGMA_COLUMNS@
+PRAGMA_SYSTEM_HEADER = @PRAGMA_SYSTEM_HEADER@
+PRIPTR_PREFIX = @PRIPTR_PREFIX@
+PRI_MACROS_BROKEN = @PRI_MACROS_BROKEN@
+PR_PROGRAM = @PR_PROGRAM@
+PTHREAD_H_DEFINES_STRUCT_TIMESPEC = @PTHREAD_H_DEFINES_STRUCT_TIMESPEC@
+PTRDIFF_T_SUFFIX = @PTRDIFF_T_SUFFIX@
+RANLIB = @RANLIB@
+REPLACE_BTOWC = @REPLACE_BTOWC@
+REPLACE_CALLOC = @REPLACE_CALLOC@
+REPLACE_CANONICALIZE_FILE_NAME = @REPLACE_CANONICALIZE_FILE_NAME@
+REPLACE_CHOWN = @REPLACE_CHOWN@
+REPLACE_CLOSE = @REPLACE_CLOSE@
+REPLACE_DPRINTF = @REPLACE_DPRINTF@
+REPLACE_DUP = @REPLACE_DUP@
+REPLACE_DUP2 = @REPLACE_DUP2@
+REPLACE_DUPLOCALE = @REPLACE_DUPLOCALE@
+REPLACE_FCHOWNAT = @REPLACE_FCHOWNAT@
+REPLACE_FCLOSE = @REPLACE_FCLOSE@
+REPLACE_FCNTL = @REPLACE_FCNTL@
+REPLACE_FDOPEN = @REPLACE_FDOPEN@
+REPLACE_FFLUSH = @REPLACE_FFLUSH@
+REPLACE_FOPEN = @REPLACE_FOPEN@
+REPLACE_FPRINTF = @REPLACE_FPRINTF@
+REPLACE_FPURGE = @REPLACE_FPURGE@
+REPLACE_FREOPEN = @REPLACE_FREOPEN@
+REPLACE_FSEEK = @REPLACE_FSEEK@
+REPLACE_FSEEKO = @REPLACE_FSEEKO@
+REPLACE_FSTAT = @REPLACE_FSTAT@
+REPLACE_FSTATAT = @REPLACE_FSTATAT@
+REPLACE_FTELL = @REPLACE_FTELL@
+REPLACE_FTELLO = @REPLACE_FTELLO@
+REPLACE_FTRUNCATE = @REPLACE_FTRUNCATE@
+REPLACE_FUTIMENS = @REPLACE_FUTIMENS@
+REPLACE_GETCWD = @REPLACE_GETCWD@
+REPLACE_GETDELIM = @REPLACE_GETDELIM@
+REPLACE_GETDOMAINNAME = @REPLACE_GETDOMAINNAME@
+REPLACE_GETDTABLESIZE = @REPLACE_GETDTABLESIZE@
+REPLACE_GETGROUPS = @REPLACE_GETGROUPS@
+REPLACE_GETLINE = @REPLACE_GETLINE@
+REPLACE_GETLOGIN_R = @REPLACE_GETLOGIN_R@
+REPLACE_GETPAGESIZE = @REPLACE_GETPAGESIZE@
+REPLACE_GETTIMEOFDAY = @REPLACE_GETTIMEOFDAY@
+REPLACE_GMTIME = @REPLACE_GMTIME@
+REPLACE_ICONV = @REPLACE_ICONV@
+REPLACE_ICONV_OPEN = @REPLACE_ICONV_OPEN@
+REPLACE_ICONV_UTF = @REPLACE_ICONV_UTF@
+REPLACE_INET_NTOP = @REPLACE_INET_NTOP@
+REPLACE_INET_PTON = @REPLACE_INET_PTON@
+REPLACE_IOCTL = @REPLACE_IOCTL@
+REPLACE_ISATTY = @REPLACE_ISATTY@
+REPLACE_ISWBLANK = @REPLACE_ISWBLANK@
+REPLACE_ISWCNTRL = @REPLACE_ISWCNTRL@
+REPLACE_ITOLD = @REPLACE_ITOLD@
+REPLACE_LCHOWN = @REPLACE_LCHOWN@
+REPLACE_LINK = @REPLACE_LINK@
+REPLACE_LINKAT = @REPLACE_LINKAT@
+REPLACE_LOCALECONV = @REPLACE_LOCALECONV@
+REPLACE_LOCALTIME = @REPLACE_LOCALTIME@
+REPLACE_LOCALTIME_R = @REPLACE_LOCALTIME_R@
+REPLACE_LSEEK = @REPLACE_LSEEK@
+REPLACE_LSTAT = @REPLACE_LSTAT@
+REPLACE_MALLOC = @REPLACE_MALLOC@
+REPLACE_MBRLEN = @REPLACE_MBRLEN@
+REPLACE_MBRTOWC = @REPLACE_MBRTOWC@
+REPLACE_MBSINIT = @REPLACE_MBSINIT@
+REPLACE_MBSNRTOWCS = @REPLACE_MBSNRTOWCS@
+REPLACE_MBSRTOWCS = @REPLACE_MBSRTOWCS@
+REPLACE_MBSTATE_T = @REPLACE_MBSTATE_T@
+REPLACE_MBTOWC = @REPLACE_MBTOWC@
+REPLACE_MEMCHR = @REPLACE_MEMCHR@
+REPLACE_MEMMEM = @REPLACE_MEMMEM@
+REPLACE_MKDIR = @REPLACE_MKDIR@
+REPLACE_MKFIFO = @REPLACE_MKFIFO@
+REPLACE_MKNOD = @REPLACE_MKNOD@
+REPLACE_MKSTEMP = @REPLACE_MKSTEMP@
+REPLACE_MKTIME = @REPLACE_MKTIME@
+REPLACE_NANOSLEEP = @REPLACE_NANOSLEEP@
+REPLACE_NL_LANGINFO = @REPLACE_NL_LANGINFO@
+REPLACE_NULL = @REPLACE_NULL@
+REPLACE_OBSTACK_PRINTF = @REPLACE_OBSTACK_PRINTF@
+REPLACE_OPEN = @REPLACE_OPEN@
+REPLACE_OPENAT = @REPLACE_OPENAT@
+REPLACE_PERROR = @REPLACE_PERROR@
+REPLACE_POPEN = @REPLACE_POPEN@
+REPLACE_PREAD = @REPLACE_PREAD@
+REPLACE_PRINTF = @REPLACE_PRINTF@
+REPLACE_PSELECT = @REPLACE_PSELECT@
+REPLACE_PTHREAD_SIGMASK = @REPLACE_PTHREAD_SIGMASK@
+REPLACE_PTSNAME = @REPLACE_PTSNAME@
+REPLACE_PTSNAME_R = @REPLACE_PTSNAME_R@
+REPLACE_PUTENV = @REPLACE_PUTENV@
+REPLACE_PWRITE = @REPLACE_PWRITE@
+REPLACE_QSORT_R = @REPLACE_QSORT_R@
+REPLACE_RAISE = @REPLACE_RAISE@
+REPLACE_RANDOM_R = @REPLACE_RANDOM_R@
+REPLACE_READ = @REPLACE_READ@
+REPLACE_READLINK = @REPLACE_READLINK@
+REPLACE_READLINKAT = @REPLACE_READLINKAT@
+REPLACE_REALLOC = @REPLACE_REALLOC@
+REPLACE_REALPATH = @REPLACE_REALPATH@
+REPLACE_REMOVE = @REPLACE_REMOVE@
+REPLACE_RENAME = @REPLACE_RENAME@
+REPLACE_RENAMEAT = @REPLACE_RENAMEAT@
+REPLACE_RMDIR = @REPLACE_RMDIR@
+REPLACE_SELECT = @REPLACE_SELECT@
+REPLACE_SETENV = @REPLACE_SETENV@
+REPLACE_SETLOCALE = @REPLACE_SETLOCALE@
+REPLACE_SLEEP = @REPLACE_SLEEP@
+REPLACE_SNPRINTF = @REPLACE_SNPRINTF@
+REPLACE_SPRINTF = @REPLACE_SPRINTF@
+REPLACE_STAT = @REPLACE_STAT@
+REPLACE_STDIO_READ_FUNCS = @REPLACE_STDIO_READ_FUNCS@
+REPLACE_STDIO_WRITE_FUNCS = @REPLACE_STDIO_WRITE_FUNCS@
+REPLACE_STPNCPY = @REPLACE_STPNCPY@
+REPLACE_STRCASESTR = @REPLACE_STRCASESTR@
+REPLACE_STRCHRNUL = @REPLACE_STRCHRNUL@
+REPLACE_STRDUP = @REPLACE_STRDUP@
+REPLACE_STRERROR = @REPLACE_STRERROR@
+REPLACE_STRERROR_R = @REPLACE_STRERROR_R@
+REPLACE_STRNCAT = @REPLACE_STRNCAT@
+REPLACE_STRNDUP = @REPLACE_STRNDUP@
+REPLACE_STRNLEN = @REPLACE_STRNLEN@
+REPLACE_STRSIGNAL = @REPLACE_STRSIGNAL@
+REPLACE_STRSTR = @REPLACE_STRSTR@
+REPLACE_STRTOD = @REPLACE_STRTOD@
+REPLACE_STRTOIMAX = @REPLACE_STRTOIMAX@
+REPLACE_STRTOK_R = @REPLACE_STRTOK_R@
+REPLACE_STRTOUMAX = @REPLACE_STRTOUMAX@
+REPLACE_STRUCT_LCONV = @REPLACE_STRUCT_LCONV@
+REPLACE_STRUCT_TIMEVAL = @REPLACE_STRUCT_TIMEVAL@
+REPLACE_SYMLINK = @REPLACE_SYMLINK@
+REPLACE_SYMLINKAT = @REPLACE_SYMLINKAT@
+REPLACE_TIMEGM = @REPLACE_TIMEGM@
+REPLACE_TMPFILE = @REPLACE_TMPFILE@
+REPLACE_TOWLOWER = @REPLACE_TOWLOWER@
+REPLACE_TTYNAME_R = @REPLACE_TTYNAME_R@
+REPLACE_UNLINK = @REPLACE_UNLINK@
+REPLACE_UNLINKAT = @REPLACE_UNLINKAT@
+REPLACE_UNSETENV = @REPLACE_UNSETENV@
+REPLACE_USLEEP = @REPLACE_USLEEP@
+REPLACE_UTIMENSAT = @REPLACE_UTIMENSAT@
+REPLACE_VASPRINTF = @REPLACE_VASPRINTF@
+REPLACE_VDPRINTF = @REPLACE_VDPRINTF@
+REPLACE_VFPRINTF = @REPLACE_VFPRINTF@
+REPLACE_VPRINTF = @REPLACE_VPRINTF@
+REPLACE_VSNPRINTF = @REPLACE_VSNPRINTF@
+REPLACE_VSPRINTF = @REPLACE_VSPRINTF@
+REPLACE_WCRTOMB = @REPLACE_WCRTOMB@
+REPLACE_WCSNRTOMBS = @REPLACE_WCSNRTOMBS@
+REPLACE_WCSRTOMBS = @REPLACE_WCSRTOMBS@
+REPLACE_WCSWIDTH = @REPLACE_WCSWIDTH@
+REPLACE_WCTOB = @REPLACE_WCTOB@
+REPLACE_WCTOMB = @REPLACE_WCTOMB@
+REPLACE_WCWIDTH = @REPLACE_WCWIDTH@
+REPLACE_WRITE = @REPLACE_WRITE@
+SED = @SED@
+SET_MAKE = @SET_MAKE@
+SHELL = @SHELL@
+SIG_ATOMIC_T_SUFFIX = @SIG_ATOMIC_T_SUFFIX@
+SIZE_T_SUFFIX = @SIZE_T_SUFFIX@
+SRC_VERSION_C = @SRC_VERSION_C@
+STDALIGN_H = @STDALIGN_H@
+STDARG_H = @STDARG_H@
+STDBOOL_H = @STDBOOL_H@
+STDDEF_H = @STDDEF_H@
+STDINT_H = @STDINT_H@
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diff --git a/doc/diagmeet.note b/doc/diagmeet.note
new file mode 100644
index 0000000..2d30d21
--- /dev/null
+++ b/doc/diagmeet.note
@@ -0,0 +1,62 @@
+Here is a comparison matrix which shows a case in which
+it is possible for the forward and backward scan in 'diag'
+to meet along a nonzero length of diagonal simultaneous
+(so that bdiag[d] and fdiag[d] are not equal)
+even though there is no snake on that diagonal at the meeting point.
+
+
+ 85 1 1 1 159 1 1 17
+ 1 2 3 4
+60
+ 1 2
+1
+ 2 2 3 4
+71
+ 3 3 4 5
+85
+ 4 3 4 5
+17
+ 5 4 5
+1
+ 6 4 5 6
+183
+ 7 5 6 7
+10
+ 8 6 7
+1
+ 9 6 7 8
+12
+ 7 8 9 10
+13
+ 10 8 9 10
+14
+ 10 9 10
+17
+ 10 10
+1
+ 10 9 10
+1
+ 8 10 10 10
+183
+ 8 7 9 9 9
+10
+ 7 6 8 9 8 8
+1
+ 6 5 7 7
+1
+ 5 6 6
+1
+ 5 5 5
+50
+ 5 4 4 4
+1
+ 4 3 3
+85
+ 5 4 3 2 2
+1
+ 2 1
+17
+ 5 4 3 2 1 1
+1
+ 1 0
+ 85 1 1 1 159 1 1 17
diff --git a/doc/diffutils.info b/doc/diffutils.info
new file mode 100644
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--- /dev/null
+++ b/doc/diffutils.info
@@ -0,0 +1,5313 @@
+This is diffutils.info-t, produced by makeinfo version 6.1 from
+diffutils.texi.
+
+This manual is for GNU Diffutils (version 3.5, 4 August 2016), and
+documents the GNU 'diff', 'diff3', 'sdiff', and 'cmp' commands for
+showing the differences between files and the GNU 'patch' command for
+using their output to update files.
+
+ Copyright (C) 1992-1994, 1998, 2001-2002, 2004, 2006, 2009-2016 Free
+Software Foundation, Inc.
+
+ Permission is granted to copy, distribute and/or modify this
+ document under the terms of the GNU Free Documentation License,
+ Version 1.3 or any later version published by the Free Software
+ Foundation; with no Invariant Sections, no Front-Cover Texts, and
+ no Back-Cover Texts. A copy of the license is included in the
+ section entitled "GNU Free Documentation License."
+INFO-DIR-SECTION Individual utilities
+START-INFO-DIR-ENTRY
+* cmp: (diffutils)Invoking cmp. Compare 2 files byte by byte.
+* diff: (diffutils)Invoking diff. Compare 2 files line by line.
+* diff3: (diffutils)Invoking diff3. Compare 3 files line by line.
+* patch: (diffutils)Invoking patch. Apply a patch to a file.
+* sdiff: (diffutils)Invoking sdiff. Merge 2 files side-by-side.
+END-INFO-DIR-ENTRY
+
+INFO-DIR-SECTION Text creation and manipulation
+START-INFO-DIR-ENTRY
+* Diffutils: (diffutils). Comparing and merging files.
+END-INFO-DIR-ENTRY
+
+
+File: diffutils.info-t, Node: Top, Next: Overview, Up: (dir)
+
+Comparing and Merging Files
+***************************
+
+This manual is for GNU Diffutils (version 3.5, 4 August 2016), and
+documents the GNU 'diff', 'diff3', 'sdiff', and 'cmp' commands for
+showing the differences between files and the GNU 'patch' command for
+using their output to update files.
+
+ Copyright (C) 1992-1994, 1998, 2001-2002, 2004, 2006, 2009-2016 Free
+Software Foundation, Inc.
+
+ Permission is granted to copy, distribute and/or modify this
+ document under the terms of the GNU Free Documentation License,
+ Version 1.3 or any later version published by the Free Software
+ Foundation; with no Invariant Sections, no Front-Cover Texts, and
+ no Back-Cover Texts. A copy of the license is included in the
+ section entitled "GNU Free Documentation License."
+
+* Menu:
+
+* Overview:: Preliminary information.
+* Comparison:: What file comparison means.
+
+* Output Formats:: Formats for two-way difference reports.
+* Incomplete Lines:: Lines that lack trailing newlines.
+* Comparing Directories:: Comparing files and directories.
+* Adjusting Output:: Making 'diff' output prettier.
+* diff Performance:: Making 'diff' smarter or faster.
+
+* Comparing Three Files:: Formats for three-way difference reports.
+* diff3 Merging:: Merging from a common ancestor.
+
+* Interactive Merging:: Interactive merging with 'sdiff'.
+
+* Merging with patch:: Using 'patch' to change old files into new ones.
+* Making Patches:: Tips for making and using patch distributions.
+
+* Invoking cmp:: Compare two files byte by byte.
+* Invoking diff:: Compare two files line by line.
+* Invoking diff3:: Compare three files line by line.
+* Invoking patch:: Apply a diff file to an original.
+* Invoking sdiff:: Side-by-side merge of file differences.
+
+* Standards conformance:: Conformance to the POSIX standard.
+* Projects:: If you've found a bug or other shortcoming.
+
+* Copying This Manual:: How to make copies of this manual.
+* Translations:: Available translations of this manual.
+* Index:: Index.
+
+
+File: diffutils.info-t, Node: Overview, Next: Comparison, Prev: Top, Up: Top
+
+Overview
+********
+
+Computer users often find occasion to ask how two files differ. Perhaps
+one file is a newer version of the other file. Or maybe the two files
+started out as identical copies but were changed by different people.
+
+ You can use the 'diff' command to show differences between two files,
+or each corresponding file in two directories. 'diff' outputs
+differences between files line by line in any of several formats,
+selectable by command line options. This set of differences is often
+called a "diff" or "patch". For files that are identical, 'diff'
+normally produces no output; for binary (non-text) files, 'diff'
+normally reports only that they are different.
+
+ You can use the 'cmp' command to show the byte and line numbers where
+two files differ. 'cmp' can also show all the bytes that differ between
+the two files, side by side. A way to compare two files character by
+character is the Emacs command 'M-x compare-windows'. *Note Other
+Window: (emacs)Other Window, for more information on that command.
+
+ You can use the 'diff3' command to show differences among three
+files. When two people have made independent changes to a common
+original, 'diff3' can report the differences between the original and
+the two changed versions, and can produce a merged file that contains
+both persons' changes together with warnings about conflicts.
+
+ You can use the 'sdiff' command to merge two files interactively.
+
+ You can use the set of differences produced by 'diff' to distribute
+updates to text files (such as program source code) to other people.
+This method is especially useful when the differences are small compared
+to the complete files. Given 'diff' output, you can use the 'patch'
+program to update, or "patch", a copy of the file. If you think of
+'diff' as subtracting one file from another to produce their difference,
+you can think of 'patch' as adding the difference to one file to
+reproduce the other.
+
+ This manual first concentrates on making diffs, and later shows how
+to use diffs to update files.
+
+ GNU 'diff' was written by Paul Eggert, Mike Haertel, David Hayes,
+Richard Stallman, and Len Tower. Wayne Davison designed and implemented
+the unified output format. The basic algorithm is described by Eugene
+W. Myers in "An O(ND) Difference Algorithm and its Variations",
+'Algorithmica' Vol. 1, 1986, pp. 251-266,
+<http://dx.doi.org/10.1007/BF01840446>; and in "A File Comparison
+Program", Webb Miller and Eugene W. Myers, 'Software--Practice and
+Experience' Vol. 15, 1985, pp. 1025-1040,
+<http://dx.doi.org/10.1002/spe.4380151102>. The algorithm was
+independently discovered as described by Esko Ukkonen in "Algorithms for
+Approximate String Matching", 'Information and Control' Vol. 64, 1985,
+pp. 100-118, <http://dx.doi.org/10.1016/S0019-9958(85)80046-2>. Related
+algorithms are surveyed by Alfred V. Aho in section 6.3 of "Algorithms
+for Finding Patterns in Strings", 'Handbook of Theoretical Computer
+Science' (Jan Van Leeuwen, ed.), Vol. A, 'Algorithms and Complexity',
+Elsevier/MIT Press, 1990, pp. 255-300.
+
+ GNU 'diff3' was written by Randy Smith. GNU 'sdiff' was written by
+Thomas Lord. GNU 'cmp' was written by Torbjo"rn Granlund and David
+MacKenzie.
+
+ GNU 'patch' was written mainly by Larry Wall and Paul Eggert; several
+GNU enhancements were contributed by Wayne Davison and David MacKenzie.
+Parts of this manual are adapted from a manual page written by Larry
+Wall, with his permission.
+
+
+File: diffutils.info-t, Node: Comparison, Next: Output Formats, Prev: Overview, Up: Top
+
+1 What Comparison Means
+***********************
+
+There are several ways to think about the differences between two files.
+One way to think of the differences is as a series of lines that were
+deleted from, inserted in, or changed in one file to produce the other
+file. 'diff' compares two files line by line, finds groups of lines
+that differ, and reports each group of differing lines. It can report
+the differing lines in several formats, which have different purposes.
+
+ GNU 'diff' can show whether files are different without detailing the
+differences. It also provides ways to suppress certain kinds of
+differences that are not important to you. Most commonly, such
+differences are changes in the amount of white space between words or
+lines. 'diff' also provides ways to suppress differences in alphabetic
+case or in lines that match a regular expression that you provide.
+These options can accumulate; for example, you can ignore changes in
+both white space and alphabetic case.
+
+ Another way to think of the differences between two files is as a
+sequence of pairs of bytes that can be either identical or different.
+'cmp' reports the differences between two files byte by byte, instead of
+line by line. As a result, it is often more useful than 'diff' for
+comparing binary files. For text files, 'cmp' is useful mainly when you
+want to know only whether two files are identical, or whether one file
+is a prefix of the other.
+
+ To illustrate the effect that considering changes byte by byte can
+have compared with considering them line by line, think of what happens
+if a single newline character is added to the beginning of a file. If
+that file is then compared with an otherwise identical file that lacks
+the newline at the beginning, 'diff' will report that a blank line has
+been added to the file, while 'cmp' will report that almost every byte
+of the two files differs.
+
+ 'diff3' normally compares three input files line by line, finds
+groups of lines that differ, and reports each group of differing lines.
+Its output is designed to make it easy to inspect two different sets of
+changes to the same file.
+
+ These commands compare input files without necessarily reading them.
+For example, if 'diff' is asked simply to report whether two files
+differ, and it discovers that the files have different sizes, it need
+not read them to do its job.
+
+* Menu:
+
+* Hunks:: Groups of differing lines.
+* White Space:: Suppressing differences in white space.
+* Blank Lines:: Suppressing differences whose lines are all blank.
+* Specified Lines:: Suppressing differences whose lines all match a pattern.
+* Case Folding:: Suppressing differences in alphabetic case.
+* Brief:: Summarizing which files are different.
+* Binary:: Comparing binary files or forcing text comparisons.
+
+
+File: diffutils.info-t, Node: Hunks, Next: White Space, Up: Comparison
+
+1.1 Hunks
+=========
+
+When comparing two files, 'diff' finds sequences of lines common to both
+files, interspersed with groups of differing lines called "hunks".
+Comparing two identical files yields one sequence of common lines and no
+hunks, because no lines differ. Comparing two entirely different files
+yields no common lines and one large hunk that contains all lines of
+both files. In general, there are many ways to match up lines between
+two given files. 'diff' tries to minimize the total hunk size by
+finding large sequences of common lines interspersed with small hunks of
+differing lines.
+
+ For example, suppose the file 'F' contains the three lines 'a', 'b',
+'c', and the file 'G' contains the same three lines in reverse order
+'c', 'b', 'a'. If 'diff' finds the line 'c' as common, then the command
+'diff F G' produces this output:
+
+ 1,2d0
+ < a
+ < b
+ 3a2,3
+ > b
+ > a
+
+But if 'diff' notices the common line 'b' instead, it produces this
+output:
+
+ 1c1
+ < a
+ ---
+ > c
+ 3c3
+ < c
+ ---
+ > a
+
+It is also possible to find 'a' as the common line. 'diff' does not
+always find an optimal matching between the files; it takes shortcuts to
+run faster. But its output is usually close to the shortest possible.
+You can adjust this tradeoff with the '--minimal' ('-d') option (*note
+diff Performance::).
+
+
+File: diffutils.info-t, Node: White Space, Next: Blank Lines, Prev: Hunks, Up: Comparison
+
+1.2 Suppressing Differences in Blank and Tab Spacing
+====================================================
+
+The '--ignore-tab-expansion' ('-E') option ignores the distinction
+between tabs and spaces on input. A tab is considered to be equivalent
+to the number of spaces to the next tab stop (*note Tabs::).
+
+ The '--ignore-trailing-space' ('-Z') option ignores white space at
+line end.
+
+ The '--ignore-space-change' ('-b') option is stronger than '-E' and
+'-Z' combined. It ignores white space at line end, and considers all
+other sequences of one or more white space characters within a line to
+be equivalent. With this option, 'diff' considers the following two
+lines to be equivalent, where '$' denotes the line end:
+
+ Here lyeth muche rychnesse in lytell space. -- John Heywood$
+ Here lyeth muche rychnesse in lytell space. -- John Heywood $
+
+ The '--ignore-all-space' ('-w') option is stronger still. It ignores
+differences even if one line has white space where the other line has
+none. "White space" characters include tab, vertical tab, form feed,
+carriage return, and space; some locales may define additional
+characters to be white space. With this option, 'diff' considers the
+following two lines to be equivalent, where '$' denotes the line end and
+'^M' denotes a carriage return:
+
+ Here lyeth muche rychnesse in lytell space.-- John Heywood$
+ He relyeth much erychnes seinly tells pace. --John Heywood ^M$
+
+ For many other programs newline is also a white space character, but
+'diff' is a line-oriented program and a newline character always ends a
+line. Hence the '-w' or '--ignore-all-space' option does not ignore
+newline-related changes; it ignores only other white space changes.
+
+
+File: diffutils.info-t, Node: Blank Lines, Next: Specified Lines, Prev: White Space, Up: Comparison
+
+1.3 Suppressing Differences Whose Lines Are All Blank
+=====================================================
+
+The '--ignore-blank-lines' ('-B') option ignores changes that consist
+entirely of blank lines. With this option, for example, a file
+containing
+ 1. A point is that which has no part.
+
+ 2. A line is breadthless length.
+ -- Euclid, The Elements, I
+is considered identical to a file containing
+ 1. A point is that which has no part.
+ 2. A line is breadthless length.
+
+
+ -- Euclid, The Elements, I
+
+ Normally this option affects only lines that are completely empty,
+but if you also specify an option that ignores trailing spaces, lines
+are also affected if they look empty but contain white space. In other
+words, '-B' is equivalent to '-I '^$'' by default, but it is equivalent
+to '-I '^[[:space:]]*$'' if '-b', '-w' or '-Z' is also specified.
+
+
+File: diffutils.info-t, Node: Specified Lines, Next: Case Folding, Prev: Blank Lines, Up: Comparison
+
+1.4 Suppressing Differences Whose Lines All Match a Regular Expression
+======================================================================
+
+To ignore insertions and deletions of lines that match a 'grep'-style
+regular expression, use the '--ignore-matching-lines=REGEXP' ('-I
+REGEXP') option. You should escape regular expressions that contain
+shell metacharacters to prevent the shell from expanding them. For
+example, 'diff -I '^[[:digit:]]'' ignores all changes to lines beginning
+with a digit.
+
+ However, '-I' only ignores the insertion or deletion of lines that
+contain the regular expression if every changed line in the hunk--every
+insertion and every deletion--matches the regular expression. In other
+words, for each nonignorable change, 'diff' prints the complete set of
+changes in its vicinity, including the ignorable ones.
+
+ You can specify more than one regular expression for lines to ignore
+by using more than one '-I' option. 'diff' tries to match each line
+against each regular expression.
+
+
+File: diffutils.info-t, Node: Case Folding, Next: Brief, Prev: Specified Lines, Up: Comparison
+
+1.5 Suppressing Case Differences
+================================
+
+GNU 'diff' can treat lower case letters as equivalent to their upper
+case counterparts, so that, for example, it considers 'Funky Stuff',
+'funky STUFF', and 'fUNKy stuFf' to all be the same. To request this,
+use the '-i' or '--ignore-case' option.
+
+
+File: diffutils.info-t, Node: Brief, Next: Binary, Prev: Case Folding, Up: Comparison
+
+1.6 Summarizing Which Files Differ
+==================================
+
+When you only want to find out whether files are different, and you
+don't care what the differences are, you can use the summary output
+format. In this format, instead of showing the differences between the
+files, 'diff' simply reports whether files differ. The '--brief' ('-q')
+option selects this output format.
+
+ This format is especially useful when comparing the contents of two
+directories. It is also much faster than doing the normal line by line
+comparisons, because 'diff' can stop analyzing the files as soon as it
+knows that there are any differences.
+
+ You can also get a brief indication of whether two files differ by
+using 'cmp'. For files that are identical, 'cmp' produces no output.
+When the files differ, by default, 'cmp' outputs the byte and line
+number where the first difference occurs, or reports that one file is a
+prefix of the other. You can use the '-s', '--quiet', or '--silent'
+option to suppress that information, so that 'cmp' produces no output
+and reports whether the files differ using only its exit status (*note
+Invoking cmp::).
+
+ Unlike 'diff', 'cmp' cannot compare directories; it can only compare
+two files.
+
+
+File: diffutils.info-t, Node: Binary, Prev: Brief, Up: Comparison
+
+1.7 Binary Files and Forcing Text Comparisons
+=============================================
+
+If 'diff' thinks that either of the two files it is comparing is binary
+(a non-text file), it normally treats that pair of files much as if the
+summary output format had been selected (*note Brief::), and reports
+only that the binary files are different. This is because line by line
+comparisons are usually not meaningful for binary files. This does not
+count as trouble, even though the resulting output does not capture all
+the differences.
+
+ 'diff' determines whether a file is text or binary by checking the
+first few bytes in the file; the exact number of bytes is system
+dependent, but it is typically several thousand. If every byte in that
+part of the file is non-null, 'diff' considers the file to be text;
+otherwise it considers the file to be binary.
+
+ Sometimes you might want to force 'diff' to consider files to be
+text. For example, you might be comparing text files that contain null
+characters; 'diff' would erroneously decide that those are non-text
+files. Or you might be comparing documents that are in a format used by
+a word processing system that uses null characters to indicate special
+formatting. You can force 'diff' to consider all files to be text
+files, and compare them line by line, by using the '--text' ('-a')
+option. If the files you compare using this option do not in fact
+contain text, they will probably contain few newline characters, and the
+'diff' output will consist of hunks showing differences between long
+lines of whatever characters the files contain.
+
+ You can also force 'diff' to report only whether files differ (but
+not how). Use the '--brief' ('-q') option for this.
+
+ In operating systems that distinguish between text and binary files,
+'diff' normally reads and writes all data as text. Use the '--binary'
+option to force 'diff' to read and write binary data instead. This
+option has no effect on a POSIX-compliant system like GNU or traditional
+Unix. However, many personal computer operating systems represent the
+end of a line with a carriage return followed by a newline. On such
+systems, 'diff' normally ignores these carriage returns on input and
+generates them at the end of each output line, but with the '--binary'
+option 'diff' treats each carriage return as just another input
+character, and does not generate a carriage return at the end of each
+output line. This can be useful when dealing with non-text files that
+are meant to be interchanged with POSIX-compliant systems.
+
+ The '--strip-trailing-cr' causes 'diff' to treat input lines that end
+in carriage return followed by newline as if they end in plain newline.
+This can be useful when comparing text that is imperfectly imported from
+many personal computer operating systems. This option affects how lines
+are read, which in turn affects how they are compared and output.
+
+ If you want to compare two files byte by byte, you can use the 'cmp'
+program with the '--verbose' ('-l') option to show the values of each
+differing byte in the two files. With GNU 'cmp', you can also use the
+'-b' or '--print-bytes' option to show the ASCII representation of those
+bytes. *Note Invoking cmp::, for more information.
+
+ If 'diff3' thinks that any of the files it is comparing is binary (a
+non-text file), it normally reports an error, because such comparisons
+are usually not useful. 'diff3' uses the same test as 'diff' to decide
+whether a file is binary. As with 'diff', if the input files contain a
+few non-text bytes but otherwise are like text files, you can force
+'diff3' to consider all files to be text files and compare them line by
+line by using the '-a' or '--text' option.
+
+
+File: diffutils.info-t, Node: Output Formats, Next: Incomplete Lines, Prev: Comparison, Up: Top
+
+2 'diff' Output Formats
+***********************
+
+'diff' has several mutually exclusive options for output format. The
+following sections describe each format, illustrating how 'diff' reports
+the differences between two sample input files.
+
+* Menu:
+
+* Sample diff Input:: Sample 'diff' input files for examples.
+* Context:: Showing differences with the surrounding text.
+* Side by Side:: Showing differences in two columns.
+* Normal:: Showing differences without surrounding text.
+* Scripts:: Generating scripts for other programs.
+* If-then-else:: Merging files with if-then-else.
+
+
+File: diffutils.info-t, Node: Sample diff Input, Next: Context, Up: Output Formats
+
+2.1 Two Sample Input Files
+==========================
+
+Here are two sample files that we will use in numerous examples to
+illustrate the output of 'diff' and how various options can change it.
+
+ This is the file 'lao':
+
+ The Way that can be told of is not the eternal Way;
+ The name that can be named is not the eternal name.
+ The Nameless is the origin of Heaven and Earth;
+ The Named is the mother of all things.
+ Therefore let there always be non-being,
+ so we may see their subtlety,
+ And let there always be being,
+ so we may see their outcome.
+ The two are the same,
+ But after they are produced,
+ they have different names.
+
+ This is the file 'tzu':
+
+ The Nameless is the origin of Heaven and Earth;
+ The named is the mother of all things.
+
+ Therefore let there always be non-being,
+ so we may see their subtlety,
+ And let there always be being,
+ so we may see their outcome.
+ The two are the same,
+ But after they are produced,
+ they have different names.
+ They both may be called deep and profound.
+ Deeper and more profound,
+ The door of all subtleties!
+
+ In this example, the first hunk contains just the first two lines of
+'lao', the second hunk contains the fourth line of 'lao' opposing the
+second and third lines of 'tzu', and the last hunk contains just the
+last three lines of 'tzu'.
+
+
+File: diffutils.info-t, Node: Context, Next: Side by Side, Prev: Sample diff Input, Up: Output Formats
+
+2.2 Showing Differences in Their Context
+========================================
+
+Usually, when you are looking at the differences between files, you will
+also want to see the parts of the files near the lines that differ, to
+help you understand exactly what has changed. These nearby parts of the
+files are called the "context".
+
+ GNU 'diff' provides two output formats that show context around the
+differing lines: "context format" and "unified format". It can
+optionally show in which function or section of the file the differing
+lines are found.
+
+ If you are distributing new versions of files to other people in the
+form of 'diff' output, you should use one of the output formats that
+show context so that they can apply the diffs even if they have made
+small changes of their own to the files. 'patch' can apply the diffs in
+this case by searching in the files for the lines of context around the
+differing lines; if those lines are actually a few lines away from where
+the diff says they are, 'patch' can adjust the line numbers accordingly
+and still apply the diff correctly. *Note Imperfect::, for more
+information on using 'patch' to apply imperfect diffs.
+
+* Menu:
+
+* Context Format:: An output format that shows surrounding lines.
+* Unified Format:: A more compact output format that shows context.
+* Sections:: Showing which sections of the files differences are in.
+* Alternate Names:: Showing alternate file names in context headers.
+
+
+File: diffutils.info-t, Node: Context Format, Next: Unified Format, Up: Context
+
+2.2.1 Context Format
+--------------------
+
+The context output format shows several lines of context around the
+lines that differ. It is the standard format for distributing updates
+to source code.
+
+ To select this output format, use the '--context[=LINES]' ('-C
+LINES') or '-c' option. The argument LINES that some of these options
+take is the number of lines of context to show. If you do not specify
+LINES, it defaults to three. For proper operation, 'patch' typically
+needs at least two lines of context.
+
+* Menu:
+
+* Example Context:: Sample output in context format.
+* Less Context:: Another sample with less context.
+* Detailed Context:: A detailed description of the context output format.
+
+
+File: diffutils.info-t, Node: Example Context, Next: Less Context, Up: Context Format
+
+2.2.1.1 An Example of Context Format
+....................................
+
+Here is the output of 'diff -c lao tzu' (*note Sample diff Input::, for
+the complete contents of the two files). Notice that up to three lines
+that are not different are shown around each line that is different;
+they are the context lines. Also notice that the first two hunks have
+run together, because their contents overlap.
+
+ *** lao 2002-02-21 23:30:39.942229878 -0800
+ --- tzu 2002-02-21 23:30:50.442260588 -0800
+ ***************
+ *** 1,7 ****
+ - The Way that can be told of is not the eternal Way;
+ - The name that can be named is not the eternal name.
+ The Nameless is the origin of Heaven and Earth;
+ ! The Named is the mother of all things.
+ Therefore let there always be non-being,
+ so we may see their subtlety,
+ And let there always be being,
+ --- 1,6 ----
+ The Nameless is the origin of Heaven and Earth;
+ ! The named is the mother of all things.
+ !
+ Therefore let there always be non-being,
+ so we may see their subtlety,
+ And let there always be being,
+ ***************
+ *** 9,11 ****
+ --- 8,13 ----
+ The two are the same,
+ But after they are produced,
+ they have different names.
+ + They both may be called deep and profound.
+ + Deeper and more profound,
+ + The door of all subtleties!
+
+
+File: diffutils.info-t, Node: Less Context, Next: Detailed Context, Prev: Example Context, Up: Context Format
+
+2.2.1.2 An Example of Context Format with Less Context
+......................................................
+
+Here is the output of 'diff -C 1 lao tzu' (*note Sample diff Input::,
+for the complete contents of the two files). Notice that at most one
+context line is reported here.
+
+ *** lao 2002-02-21 23:30:39.942229878 -0800
+ --- tzu 2002-02-21 23:30:50.442260588 -0800
+ ***************
+ *** 1,5 ****
+ - The Way that can be told of is not the eternal Way;
+ - The name that can be named is not the eternal name.
+ The Nameless is the origin of Heaven and Earth;
+ ! The Named is the mother of all things.
+ Therefore let there always be non-being,
+ --- 1,4 ----
+ The Nameless is the origin of Heaven and Earth;
+ ! The named is the mother of all things.
+ !
+ Therefore let there always be non-being,
+ ***************
+ *** 11 ****
+ --- 10,13 ----
+ they have different names.
+ + They both may be called deep and profound.
+ + Deeper and more profound,
+ + The door of all subtleties!
+
+
+File: diffutils.info-t, Node: Detailed Context, Prev: Less Context, Up: Context Format
+
+2.2.1.3 Detailed Description of Context Format
+..............................................
+
+The context output format starts with a two-line header, which looks
+like this:
+
+ *** FROM-FILE FROM-FILE-MODIFICATION-TIME
+ --- TO-FILE TO-FILE-MODIFICATION TIME
+
+The time stamp normally looks like '2002-02-21 23:30:39.942229878 -0800'
+to indicate the date, time with fractional seconds, and time zone in
+Internet RFC 2822 format (ftp://ftp.isi.edu/in-notes/rfc2822.txt). (The
+fractional seconds are omitted on hosts that do not support fractional
+time stamps.) However, a traditional time stamp like 'Thu Feb 21
+23:30:39 2002' is used if the 'LC_TIME' locale category is either 'C' or
+'POSIX'.
+
+ You can change the header's content with the '--label=LABEL' option;
+see *note Alternate Names::.
+
+ Next come one or more hunks of differences; each hunk shows one area
+where the files differ. Context format hunks look like this:
+
+ ***************
+ *** FROM-FILE-LINE-NUMBERS ****
+ FROM-FILE-LINE
+ FROM-FILE-LINE...
+ --- TO-FILE-LINE-NUMBERS ----
+ TO-FILE-LINE
+ TO-FILE-LINE...
+
+ If a hunk contains two or more lines, its line numbers look like
+'START,END'. Otherwise only its end line number appears. An empty hunk
+is considered to end at the line that precedes the hunk.
+
+ The lines of context around the lines that differ start with two
+space characters. The lines that differ between the two files start
+with one of the following indicator characters, followed by a space
+character:
+
+'!'
+ A line that is part of a group of one or more lines that changed
+ between the two files. There is a corresponding group of lines
+ marked with '!' in the part of this hunk for the other file.
+
+'+'
+ An "inserted" line in the second file that corresponds to nothing
+ in the first file.
+
+'-'
+ A "deleted" line in the first file that corresponds to nothing in
+ the second file.
+
+ If all of the changes in a hunk are insertions, the lines of
+FROM-FILE are omitted. If all of the changes are deletions, the lines
+of TO-FILE are omitted.
+
+
+File: diffutils.info-t, Node: Unified Format, Next: Sections, Prev: Context Format, Up: Context
+
+2.2.2 Unified Format
+--------------------
+
+The unified output format is a variation on the context format that is
+more compact because it omits redundant context lines. To select this
+output format, use the '--unified[=LINES]' ('-U LINES'), or '-u' option.
+The argument LINES is the number of lines of context to show. When it
+is not given, it defaults to three.
+
+ At present, only GNU 'diff' can produce this format and only GNU
+'patch' can automatically apply diffs in this format. For proper
+operation, 'patch' typically needs at least three lines of context.
+
+* Menu:
+
+* Example Unified:: Sample output in unified format.
+* Detailed Unified:: A detailed description of unified format.
+
+
+File: diffutils.info-t, Node: Example Unified, Next: Detailed Unified, Up: Unified Format
+
+2.2.2.1 An Example of Unified Format
+....................................
+
+Here is the output of the command 'diff -u lao tzu' (*note Sample diff
+Input::, for the complete contents of the two files):
+
+ --- lao 2002-02-21 23:30:39.942229878 -0800
+ +++ tzu 2002-02-21 23:30:50.442260588 -0800
+ @@ -1,7 +1,6 @@
+ -The Way that can be told of is not the eternal Way;
+ -The name that can be named is not the eternal name.
+ The Nameless is the origin of Heaven and Earth;
+ -The Named is the mother of all things.
+ +The named is the mother of all things.
+ +
+ Therefore let there always be non-being,
+ so we may see their subtlety,
+ And let there always be being,
+ @@ -9,3 +8,6 @@
+ The two are the same,
+ But after they are produced,
+ they have different names.
+ +They both may be called deep and profound.
+ +Deeper and more profound,
+ +The door of all subtleties!
+
+
+File: diffutils.info-t, Node: Detailed Unified, Prev: Example Unified, Up: Unified Format
+
+2.2.2.2 Detailed Description of Unified Format
+..............................................
+
+The unified output format starts with a two-line header, which looks
+like this:
+
+ --- FROM-FILE FROM-FILE-MODIFICATION-TIME
+ +++ TO-FILE TO-FILE-MODIFICATION-TIME
+
+The time stamp looks like '2002-02-21 23:30:39.942229878 -0800' to
+indicate the date, time with fractional seconds, and time zone. The
+fractional seconds are omitted on hosts that do not support fractional
+time stamps.
+
+ You can change the header's content with the '--label=LABEL' option.
+*Note Alternate Names::.
+
+ Next come one or more hunks of differences; each hunk shows one area
+where the files differ. Unified format hunks look like this:
+
+ @@ FROM-FILE-LINE-NUMBERS TO-FILE-LINE-NUMBERS @@
+ LINE-FROM-EITHER-FILE
+ LINE-FROM-EITHER-FILE...
+
+ If a hunk contains just one line, only its start line number appears.
+Otherwise its line numbers look like 'START,COUNT'. An empty hunk is
+considered to start at the line that follows the hunk.
+
+ If a hunk and its context contain two or more lines, its line numbers
+look like 'START,COUNT'. Otherwise only its end line number appears.
+An empty hunk is considered to end at the line that precedes the hunk.
+
+ The lines common to both files begin with a space character. The
+lines that actually differ between the two files have one of the
+following indicator characters in the left print column:
+
+'+'
+ A line was added here to the first file.
+
+'-'
+ A line was removed here from the first file.
+
+
+File: diffutils.info-t, Node: Sections, Next: Alternate Names, Prev: Unified Format, Up: Context
+
+2.2.3 Showing Which Sections Differences Are in
+-----------------------------------------------
+
+Sometimes you might want to know which part of the files each change
+falls in. If the files are source code, this could mean which function
+was changed. If the files are documents, it could mean which chapter or
+appendix was changed. GNU 'diff' can show this by displaying the
+nearest section heading line that precedes the differing lines. Which
+lines are "section headings" is determined by a regular expression.
+
+* Menu:
+
+* Specified Headings:: Showing headings that match regular expressions.
+* C Function Headings:: Showing headings of C functions.
+
+
+File: diffutils.info-t, Node: Specified Headings, Next: C Function Headings, Up: Sections
+
+2.2.3.1 Showing Lines That Match Regular Expressions
+....................................................
+
+To show in which sections differences occur for files that are not
+source code for C or similar languages, use the
+'--show-function-line=REGEXP' ('-F REGEXP') option. 'diff' considers
+lines that match the 'grep'-style regular expression REGEXP to be the
+beginning of a section of the file. Here are suggested regular
+expressions for some common languages:
+
+'^[[:alpha:]$_]'
+ C, C++, Prolog
+'^('
+ Lisp
+'^@node'
+ Texinfo
+
+ This option does not automatically select an output format; in order
+to use it, you must select the context format (*note Context Format::)
+or unified format (*note Unified Format::). In other output formats it
+has no effect.
+
+ The '--show-function-line' ('-F') option finds the nearest unchanged
+line that precedes each hunk of differences and matches the given
+regular expression. Then it adds that line to the end of the line of
+asterisks in the context format, or to the '@@' line in unified format.
+If no matching line exists, this option leaves the output for that hunk
+unchanged. If that line is more than 40 characters long, it outputs
+only the first 40 characters. You can specify more than one regular
+expression for such lines; 'diff' tries to match each line against each
+regular expression, starting with the last one given. This means that
+you can use '-p' and '-F' together, if you wish.
+
+
+File: diffutils.info-t, Node: C Function Headings, Prev: Specified Headings, Up: Sections
+
+2.2.3.2 Showing C Function Headings
+...................................
+
+To show in which functions differences occur for C and similar
+languages, you can use the '--show-c-function' ('-p') option. This
+option automatically defaults to the context output format (*note
+Context Format::), with the default number of lines of context. You can
+override that number with '-C LINES' elsewhere in the command line. You
+can override both the format and the number with '-U LINES' elsewhere in
+the command line.
+
+ The '--show-c-function' ('-p') option is equivalent to '-F
+'^[[:alpha:]$_]'' if the unified format is specified, otherwise '-c -F
+'^[[:alpha:]$_]'' (*note Specified Headings::). GNU 'diff' provides
+this option for the sake of convenience.
+
+
+File: diffutils.info-t, Node: Alternate Names, Prev: Sections, Up: Context
+
+2.2.4 Showing Alternate File Names
+----------------------------------
+
+If you are comparing two files that have meaningless or uninformative
+names, you might want 'diff' to show alternate names in the header of
+the context and unified output formats. To do this, use the
+'--label=LABEL' option. The first time you give this option, its
+argument replaces the name and date of the first file in the header; the
+second time, its argument replaces the name and date of the second file.
+If you give this option more than twice, 'diff' reports an error. The
+'--label' option does not affect the file names in the 'pr' header when
+the '-l' or '--paginate' option is used (*note Pagination::).
+
+ Here are the first two lines of the output from 'diff -C 2
+--label=original --label=modified lao tzu':
+
+ *** original
+ --- modified
+
+
+File: diffutils.info-t, Node: Side by Side, Next: Normal, Prev: Context, Up: Output Formats
+
+2.3 Showing Differences Side by Side
+====================================
+
+'diff' can produce a side by side difference listing of two files. The
+files are listed in two columns with a gutter between them. The gutter
+contains one of the following markers:
+
+white space
+ The corresponding lines are in common. That is, either the lines
+ are identical, or the difference is ignored because of one of the
+ '--ignore' options (*note White Space::).
+
+'|'
+ The corresponding lines differ, and they are either both complete
+ or both incomplete.
+
+'<'
+ The files differ and only the first file contains the line.
+
+'>'
+ The files differ and only the second file contains the line.
+
+'('
+ Only the first file contains the line, but the difference is
+ ignored.
+
+')'
+ Only the second file contains the line, but the difference is
+ ignored.
+
+'\'
+ The corresponding lines differ, and only the first line is
+ incomplete.
+
+'/'
+ The corresponding lines differ, and only the second line is
+ incomplete.
+
+ Normally, an output line is incomplete if and only if the lines that
+it contains are incomplete. *Note Incomplete Lines::. However, when an
+output line represents two differing lines, one might be incomplete
+while the other is not. In this case, the output line is complete, but
+its the gutter is marked '\' if the first line is incomplete, '/' if the
+second line is.
+
+ Side by side format is sometimes easiest to read, but it has
+limitations. It generates much wider output than usual, and truncates
+lines that are too long to fit. Also, it relies on lining up output
+more heavily than usual, so its output looks particularly bad if you use
+varying width fonts, nonstandard tab stops, or nonprinting characters.
+
+ You can use the 'sdiff' command to interactively merge side by side
+differences. *Note Interactive Merging::, for more information on
+merging files.
+
+* Menu:
+
+* Side by Side Format:: Controlling side by side output format.
+* Example Side by Side:: Sample side by side output.
+
+
+File: diffutils.info-t, Node: Side by Side Format, Next: Example Side by Side, Up: Side by Side
+
+2.3.1 Controlling Side by Side Format
+-------------------------------------
+
+The '--side-by-side' ('-y') option selects side by side format. Because
+side by side output lines contain two input lines, the output is wider
+than usual: normally 130 print columns, which can fit onto a traditional
+printer line. You can set the width of the output with the
+'--width=COLUMNS' ('-W COLUMNS') option. The output is split into two
+halves of equal width, separated by a small gutter to mark differences;
+the right half is aligned to a tab stop so that tabs line up. Input
+lines that are too long to fit in half of an output line are truncated
+for output.
+
+ The '--left-column' option prints only the left column of two common
+lines. The '--suppress-common-lines' option suppresses common lines
+entirely.
+
+
+File: diffutils.info-t, Node: Example Side by Side, Prev: Side by Side Format, Up: Side by Side
+
+2.3.2 An Example of Side by Side Format
+---------------------------------------
+
+Here is the output of the command 'diff -y -W 72 lao tzu' (*note Sample
+diff Input::, for the complete contents of the two files).
+
+ The Way that can be told of is n <
+ The name that can be named is no <
+ The Nameless is the origin of He The Nameless is the origin of He
+ The Named is the mother of all t | The named is the mother of all t
+ >
+ Therefore let there always be no Therefore let there always be no
+ so we may see their subtlety, so we may see their subtlety,
+ And let there always be being, And let there always be being,
+ so we may see their outcome. so we may see their outcome.
+ The two are the same, The two are the same,
+ But after they are produced, But after they are produced,
+ they have different names. they have different names.
+ > They both may be called deep and
+ > Deeper and more profound,
+ > The door of all subtleties!
+
+
+File: diffutils.info-t, Node: Normal, Next: Scripts, Prev: Side by Side, Up: Output Formats
+
+2.4 Showing Differences Without Context
+=======================================
+
+The "normal" 'diff' output format shows each hunk of differences without
+any surrounding context. Sometimes such output is the clearest way to
+see how lines have changed, without the clutter of nearby unchanged
+lines (although you can get similar results with the context or unified
+formats by using 0 lines of context). However, this format is no longer
+widely used for sending out patches; for that purpose, the context
+format (*note Context Format::) and the unified format (*note Unified
+Format::) are superior. Normal format is the default for compatibility
+with older versions of 'diff' and the POSIX standard. Use the
+'--normal' option to select this output format explicitly.
+
+* Menu:
+
+* Example Normal:: Sample output in the normal format.
+* Detailed Normal:: A detailed description of normal output format.
+
+
+File: diffutils.info-t, Node: Example Normal, Next: Detailed Normal, Up: Normal
+
+2.4.1 An Example of Normal Format
+---------------------------------
+
+Here is the output of the command 'diff lao tzu' (*note Sample diff
+Input::, for the complete contents of the two files). Notice that it
+shows only the lines that are different between the two files.
+
+ 1,2d0
+ < The Way that can be told of is not the eternal Way;
+ < The name that can be named is not the eternal name.
+ 4c2,3
+ < The Named is the mother of all things.
+ ---
+ > The named is the mother of all things.
+ >
+ 11a11,13
+ > They both may be called deep and profound.
+ > Deeper and more profound,
+ > The door of all subtleties!
+
+
+File: diffutils.info-t, Node: Detailed Normal, Prev: Example Normal, Up: Normal
+
+2.4.2 Detailed Description of Normal Format
+-------------------------------------------
+
+The normal output format consists of one or more hunks of differences;
+each hunk shows one area where the files differ. Normal format hunks
+look like this:
+
+ CHANGE-COMMAND
+ < FROM-FILE-LINE
+ < FROM-FILE-LINE...
+ ---
+ > TO-FILE-LINE
+ > TO-FILE-LINE...
+
+ There are three types of change commands. Each consists of a line
+number or comma-separated range of lines in the first file, a single
+character indicating the kind of change to make, and a line number or
+comma-separated range of lines in the second file. All line numbers are
+the original line numbers in each file. The types of change commands
+are:
+
+'LaR'
+ Add the lines in range R of the second file after line L of the
+ first file. For example, '8a12,15' means append lines 12-15 of
+ file 2 after line 8 of file 1; or, if changing file 2 into file 1,
+ delete lines 12-15 of file 2.
+
+'FcT'
+ Replace the lines in range F of the first file with lines in range
+ T of the second file. This is like a combined add and delete, but
+ more compact. For example, '5,7c8,10' means change lines 5-7 of
+ file 1 to read as lines 8-10 of file 2; or, if changing file 2 into
+ file 1, change lines 8-10 of file 2 to read as lines 5-7 of file 1.
+
+'RdL'
+ Delete the lines in range R from the first file; line L is where
+ they would have appeared in the second file had they not been
+ deleted. For example, '5,7d3' means delete lines 5-7 of file 1;
+ or, if changing file 2 into file 1, append lines 5-7 of file 1
+ after line 3 of file 2.
+
+
+File: diffutils.info-t, Node: Scripts, Next: If-then-else, Prev: Normal, Up: Output Formats
+
+2.5 Making Edit Scripts
+=======================
+
+Several output modes produce command scripts for editing FROM-FILE to
+produce TO-FILE.
+
+* Menu:
+
+* ed Scripts:: Using 'diff' to produce commands for 'ed'.
+* Forward ed:: Making forward 'ed' scripts.
+* RCS:: A special 'diff' output format used by RCS.
+
+
+File: diffutils.info-t, Node: ed Scripts, Next: Forward ed, Up: Scripts
+
+2.5.1 'ed' Scripts
+------------------
+
+'diff' can produce commands that direct the 'ed' text editor to change
+the first file into the second file. Long ago, this was the only output
+mode that was suitable for editing one file into another automatically;
+today, with 'patch', it is almost obsolete. Use the '--ed' ('-e')
+option to select this output format.
+
+ Like the normal format (*note Normal::), this output format does not
+show any context; unlike the normal format, it does not include the
+information necessary to apply the diff in reverse (to produce the first
+file if all you have is the second file and the diff).
+
+ If the file 'd' contains the output of 'diff -e old new', then the
+command '(cat d && echo w) | ed - old' edits 'old' to make it a copy of
+'new'. More generally, if 'd1', 'd2', ..., 'dN' contain the outputs of
+'diff -e old new1', 'diff -e new1 new2', ..., 'diff -e newN-1 newN',
+respectively, then the command '(cat d1 d2 ... dN && echo w) | ed - old'
+edits 'old' to make it a copy of 'newN'.
+
+* Menu:
+
+* Example ed:: A sample 'ed' script.
+* Detailed ed:: A detailed description of 'ed' format.
+
+
+File: diffutils.info-t, Node: Example ed, Next: Detailed ed, Up: ed Scripts
+
+2.5.1.1 Example 'ed' Script
+...........................
+
+Here is the output of 'diff -e lao tzu' (*note Sample diff Input::, for
+the complete contents of the two files):
+
+ 11a
+ They both may be called deep and profound.
+ Deeper and more profound,
+ The door of all subtleties!
+ .
+ 4c
+ The named is the mother of all things.
+
+ .
+ 1,2d
+
+
+File: diffutils.info-t, Node: Detailed ed, Prev: Example ed, Up: ed Scripts
+
+2.5.1.2 Detailed Description of 'ed' Format
+...........................................
+
+The 'ed' output format consists of one or more hunks of differences.
+The changes closest to the ends of the files come first so that commands
+that change the number of lines do not affect how 'ed' interprets line
+numbers in succeeding commands. 'ed' format hunks look like this:
+
+ CHANGE-COMMAND
+ TO-FILE-LINE
+ TO-FILE-LINE...
+ .
+
+ Because 'ed' uses a single period on a line to indicate the end of
+input, GNU 'diff' protects lines of changes that contain a single period
+on a line by writing two periods instead, then writing a subsequent 'ed'
+command to change the two periods into one. The 'ed' format cannot
+represent an incomplete line, so if the second file ends in a changed
+incomplete line, 'diff' reports an error and then pretends that a
+newline was appended.
+
+ There are three types of change commands. Each consists of a line
+number or comma-separated range of lines in the first file and a single
+character indicating the kind of change to make. All line numbers are
+the original line numbers in the file. The types of change commands
+are:
+
+'La'
+ Add text from the second file after line L in the first file. For
+ example, '8a' means to add the following lines after line 8 of file
+ 1.
+
+'Rc'
+ Replace the lines in range R in the first file with the following
+ lines. Like a combined add and delete, but more compact. For
+ example, '5,7c' means change lines 5-7 of file 1 to read as the
+ text file 2.
+
+'Rd'
+ Delete the lines in range R from the first file. For example,
+ '5,7d' means delete lines 5-7 of file 1.
+
+
+File: diffutils.info-t, Node: Forward ed, Next: RCS, Prev: ed Scripts, Up: Scripts
+
+2.5.2 Forward 'ed' Scripts
+--------------------------
+
+'diff' can produce output that is like an 'ed' script, but with hunks in
+forward (front to back) order. The format of the commands is also
+changed slightly: command characters precede the lines they modify,
+spaces separate line numbers in ranges, and no attempt is made to
+disambiguate hunk lines consisting of a single period. Like 'ed'
+format, forward 'ed' format cannot represent incomplete lines.
+
+ Forward 'ed' format is not very useful, because neither 'ed' nor
+'patch' can apply diffs in this format. It exists mainly for
+compatibility with older versions of 'diff'. Use the '-f' or
+'--forward-ed' option to select it.
+
+
+File: diffutils.info-t, Node: RCS, Prev: Forward ed, Up: Scripts
+
+2.5.3 RCS Scripts
+-----------------
+
+The RCS output format is designed specifically for use by the Revision
+Control System, which is a set of free programs used for organizing
+different versions and systems of files. Use the '--rcs' ('-n') option
+to select this output format. It is like the forward 'ed' format (*note
+Forward ed::), but it can represent arbitrary changes to the contents of
+a file because it avoids the forward 'ed' format's problems with lines
+consisting of a single period and with incomplete lines. Instead of
+ending text sections with a line consisting of a single period, each
+command specifies the number of lines it affects; a combination of the
+'a' and 'd' commands are used instead of 'c'. Also, if the second file
+ends in a changed incomplete line, then the output also ends in an
+incomplete line.
+
+ Here is the output of 'diff -n lao tzu' (*note Sample diff Input::,
+for the complete contents of the two files):
+
+ d1 2
+ d4 1
+ a4 2
+ The named is the mother of all things.
+
+ a11 3
+ They both may be called deep and profound.
+ Deeper and more profound,
+ The door of all subtleties!
+
+
+File: diffutils.info-t, Node: If-then-else, Prev: Scripts, Up: Output Formats
+
+2.6 Merging Files with If-then-else
+===================================
+
+You can use 'diff' to merge two files of C source code. The output of
+'diff' in this format contains all the lines of both files. Lines
+common to both files are output just once; the differing parts are
+separated by the C preprocessor directives '#ifdef NAME' or '#ifndef
+NAME', '#else', and '#endif'. When compiling the output, you select
+which version to use by either defining or leaving undefined the macro
+NAME.
+
+ To merge two files, use 'diff' with the '-D NAME' or '--ifdef=NAME'
+option. The argument NAME is the C preprocessor identifier to use in
+the '#ifdef' and '#ifndef' directives.
+
+ For example, if you change an instance of 'wait (&s)' to 'waitpid
+(-1, &s, 0)' and then merge the old and new files with the
+'--ifdef=HAVE_WAITPID' option, then the affected part of your code might
+look like this:
+
+ do {
+ #ifndef HAVE_WAITPID
+ if ((w = wait (&s)) < 0 && errno != EINTR)
+ #else /* HAVE_WAITPID */
+ if ((w = waitpid (-1, &s, 0)) < 0 && errno != EINTR)
+ #endif /* HAVE_WAITPID */
+ return w;
+ } while (w != child);
+
+ You can specify formats for languages other than C by using line
+group formats and line formats, as described in the next sections.
+
+* Menu:
+
+* Line Group Formats:: Formats for general if-then-else line groups.
+* Line Formats:: Formats for each line in a line group.
+* Example If-then-else:: Sample if-then-else format output.
+* Detailed If-then-else:: A detailed description of if-then-else format.
+
+
+File: diffutils.info-t, Node: Line Group Formats, Next: Line Formats, Up: If-then-else
+
+2.6.1 Line Group Formats
+------------------------
+
+Line group formats let you specify formats suitable for many
+applications that allow if-then-else input, including programming
+languages and text formatting languages. A line group format specifies
+the output format for a contiguous group of similar lines.
+
+ For example, the following command compares the TeX files 'old' and
+'new', and outputs a merged file in which old regions are surrounded by
+'\begin{em}'-'\end{em}' lines, and new regions are surrounded by
+'\begin{bf}'-'\end{bf}' lines.
+
+ diff \
+ --old-group-format='\begin{em}
+ %<\end{em}
+ ' \
+ --new-group-format='\begin{bf}
+ %>\end{bf}
+ ' \
+ old new
+
+ The following command is equivalent to the above example, but it is a
+little more verbose, because it spells out the default line group
+formats.
+
+ diff \
+ --old-group-format='\begin{em}
+ %<\end{em}
+ ' \
+ --new-group-format='\begin{bf}
+ %>\end{bf}
+ ' \
+ --unchanged-group-format='%=' \
+ --changed-group-format='\begin{em}
+ %<\end{em}
+ \begin{bf}
+ %>\end{bf}
+ ' \
+ old new
+
+ Here is a more advanced example, which outputs a diff listing with
+headers containing line numbers in a "plain English" style.
+
+ diff \
+ --unchanged-group-format='' \
+ --old-group-format='-------- %dn line%(n=1?:s) deleted at %df:
+ %<' \
+ --new-group-format='-------- %dN line%(N=1?:s) added after %de:
+ %>' \
+ --changed-group-format='-------- %dn line%(n=1?:s) changed at %df:
+ %<-------- to:
+ %>' \
+ old new
+
+ To specify a line group format, use 'diff' with one of the options
+listed below. You can specify up to four line group formats, one for
+each kind of line group. You should quote FORMAT, because it typically
+contains shell metacharacters.
+
+'--old-group-format=FORMAT'
+ These line groups are hunks containing only lines from the first
+ file. The default old group format is the same as the changed
+ group format if it is specified; otherwise it is a format that
+ outputs the line group as-is.
+
+'--new-group-format=FORMAT'
+ These line groups are hunks containing only lines from the second
+ file. The default new group format is same as the changed group
+ format if it is specified; otherwise it is a format that outputs
+ the line group as-is.
+
+'--changed-group-format=FORMAT'
+ These line groups are hunks containing lines from both files. The
+ default changed group format is the concatenation of the old and
+ new group formats.
+
+'--unchanged-group-format=FORMAT'
+ These line groups contain lines common to both files. The default
+ unchanged group format is a format that outputs the line group
+ as-is.
+
+ In a line group format, ordinary characters represent themselves;
+conversion specifications start with '%' and have one of the following
+forms.
+
+'%<'
+ stands for the lines from the first file, including the trailing
+ newline. Each line is formatted according to the old line format
+ (*note Line Formats::).
+
+'%>'
+ stands for the lines from the second file, including the trailing
+ newline. Each line is formatted according to the new line format.
+
+'%='
+ stands for the lines common to both files, including the trailing
+ newline. Each line is formatted according to the unchanged line
+ format.
+
+'%%'
+ stands for '%'.
+
+'%c'C''
+ where C is a single character, stands for C. C may not be a
+ backslash or an apostrophe. For example, '%c':'' stands for a
+ colon, even inside the then-part of an if-then-else format, which a
+ colon would normally terminate.
+
+'%c'\O''
+ where O is a string of 1, 2, or 3 octal digits, stands for the
+ character with octal code O. For example, '%c'\0'' stands for a
+ null character.
+
+'FN'
+ where F is a 'printf' conversion specification and N is one of the
+ following letters, stands for N's value formatted with F.
+
+ 'e'
+ The line number of the line just before the group in the old
+ file.
+
+ 'f'
+ The line number of the first line in the group in the old
+ file; equals E + 1.
+
+ 'l'
+ The line number of the last line in the group in the old file.
+
+ 'm'
+ The line number of the line just after the group in the old
+ file; equals L + 1.
+
+ 'n'
+ The number of lines in the group in the old file; equals L - F
+ + 1.
+
+ 'E, F, L, M, N'
+ Likewise, for lines in the new file.
+
+ The 'printf' conversion specification can be '%d', '%o', '%x', or
+ '%X', specifying decimal, octal, lower case hexadecimal, or upper
+ case hexadecimal output respectively. After the '%' the following
+ options can appear in sequence: a series of zero or more flags; an
+ integer specifying the minimum field width; and a period followed
+ by an optional integer specifying the minimum number of digits.
+ The flags are '-' for left-justification, ''' for separating the
+ digit into groups as specified by the 'LC_NUMERIC' locale category,
+ and '0' for padding with zeros instead of spaces. For example,
+ '%5dN' prints the number of new lines in the group in a field of
+ width 5 characters, using the 'printf' format '"%5d"'.
+
+'(A=B?T:E)'
+ If A equals B then T else E. A and B are each either a decimal
+ constant or a single letter interpreted as above. This format spec
+ is equivalent to T if A's value equals B's; otherwise it is
+ equivalent to E.
+
+ For example, '%(N=0?no:%dN) line%(N=1?:s)' is equivalent to 'no
+ lines' if N (the number of lines in the group in the new file) is
+ 0, to '1 line' if N is 1, and to '%dN lines' otherwise.
+
+
+File: diffutils.info-t, Node: Line Formats, Next: Example If-then-else, Prev: Line Group Formats, Up: If-then-else
+
+2.6.2 Line Formats
+------------------
+
+Line formats control how each line taken from an input file is output as
+part of a line group in if-then-else format.
+
+ For example, the following command outputs text with a one-character
+change indicator to the left of the text. The first character of output
+is '-' for deleted lines, '|' for added lines, and a space for unchanged
+lines. The formats contain newline characters where newlines are
+desired on output.
+
+ diff \
+ --old-line-format='-%l
+ ' \
+ --new-line-format='|%l
+ ' \
+ --unchanged-line-format=' %l
+ ' \
+ old new
+
+ To specify a line format, use one of the following options. You
+should quote FORMAT, since it often contains shell metacharacters.
+
+'--old-line-format=FORMAT'
+ formats lines just from the first file.
+
+'--new-line-format=FORMAT'
+ formats lines just from the second file.
+
+'--unchanged-line-format=FORMAT'
+ formats lines common to both files.
+
+'--line-format=FORMAT'
+ formats all lines; in effect, it sets all three above options
+ simultaneously.
+
+ In a line format, ordinary characters represent themselves;
+conversion specifications start with '%' and have one of the following
+forms.
+
+'%l'
+ stands for the contents of the line, not counting its trailing
+ newline (if any). This format ignores whether the line is
+ incomplete; *Note Incomplete Lines::.
+
+'%L'
+ stands for the contents of the line, including its trailing newline
+ (if any). If a line is incomplete, this format preserves its
+ incompleteness.
+
+'%%'
+ stands for '%'.
+
+'%c'C''
+ where C is a single character, stands for C. C may not be a
+ backslash or an apostrophe. For example, '%c':'' stands for a
+ colon.
+
+'%c'\O''
+ where O is a string of 1, 2, or 3 octal digits, stands for the
+ character with octal code O. For example, '%c'\0'' stands for a
+ null character.
+
+'Fn'
+ where F is a 'printf' conversion specification, stands for the line
+ number formatted with F. For example, '%.5dn' prints the line
+ number using the 'printf' format '"%.5d"'. *Note Line Group
+ Formats::, for more about printf conversion specifications.
+
+ The default line format is '%l' followed by a newline character.
+
+ If the input contains tab characters and it is important that they
+line up on output, you should ensure that '%l' or '%L' in a line format
+is just after a tab stop (e.g. by preceding '%l' or '%L' with a tab
+character), or you should use the '-t' or '--expand-tabs' option.
+
+ Taken together, the line and line group formats let you specify many
+different formats. For example, the following command uses a format
+similar to normal 'diff' format. You can tailor this command to get
+fine control over 'diff' output.
+
+ diff \
+ --old-line-format='< %l
+ ' \
+ --new-line-format='> %l
+ ' \
+ --old-group-format='%df%(f=l?:,%dl)d%dE
+ %<' \
+ --new-group-format='%dea%dF%(F=L?:,%dL)
+ %>' \
+ --changed-group-format='%df%(f=l?:,%dl)c%dF%(F=L?:,%dL)
+ %<---
+ %>' \
+ --unchanged-group-format='' \
+ old new
+
+
+File: diffutils.info-t, Node: Example If-then-else, Next: Detailed If-then-else, Prev: Line Formats, Up: If-then-else
+
+2.6.3 An Example of If-then-else Format
+---------------------------------------
+
+Here is the output of 'diff -DTWO lao tzu' (*note Sample diff Input::,
+for the complete contents of the two files):
+
+ #ifndef TWO
+ The Way that can be told of is not the eternal Way;
+ The name that can be named is not the eternal name.
+ #endif /* ! TWO */
+ The Nameless is the origin of Heaven and Earth;
+ #ifndef TWO
+ The Named is the mother of all things.
+ #else /* TWO */
+ The named is the mother of all things.
+
+ #endif /* TWO */
+ Therefore let there always be non-being,
+ so we may see their subtlety,
+ And let there always be being,
+ so we may see their outcome.
+ The two are the same,
+ But after they are produced,
+ they have different names.
+ #ifdef TWO
+ They both may be called deep and profound.
+ Deeper and more profound,
+ The door of all subtleties!
+ #endif /* TWO */
+
+
+File: diffutils.info-t, Node: Detailed If-then-else, Prev: Example If-then-else, Up: If-then-else
+
+2.6.4 Detailed Description of If-then-else Format
+-------------------------------------------------
+
+For lines common to both files, 'diff' uses the unchanged line group
+format. For each hunk of differences in the merged output format, if
+the hunk contains only lines from the first file, 'diff' uses the old
+line group format; if the hunk contains only lines from the second file,
+'diff' uses the new group format; otherwise, 'diff' uses the changed
+group format.
+
+ The old, new, and unchanged line formats specify the output format of
+lines from the first file, lines from the second file, and lines common
+to both files, respectively.
+
+ The option '--ifdef=NAME' is equivalent to the following sequence of
+options using shell syntax:
+
+ --old-group-format='#ifndef NAME
+ %<#endif /* ! NAME */
+ ' \
+ --new-group-format='#ifdef NAME
+ %>#endif /* NAME */
+ ' \
+ --unchanged-group-format='%=' \
+ --changed-group-format='#ifndef NAME
+ %<#else /* NAME */
+ %>#endif /* NAME */
+ '
+
+ You should carefully check the 'diff' output for proper nesting. For
+example, when using the '-D NAME' or '--ifdef=NAME' option, you should
+check that if the differing lines contain any of the C preprocessor
+directives '#ifdef', '#ifndef', '#else', '#elif', or '#endif', they are
+nested properly and match. If they don't, you must make corrections
+manually. It is a good idea to carefully check the resulting code
+anyway to make sure that it really does what you want it to; depending
+on how the input files were produced, the output might contain duplicate
+or otherwise incorrect code.
+
+ The 'patch' '-D NAME' option behaves like the 'diff' '-D NAME'
+option, except it operates on a file and a diff to produce a merged
+file. *Note patch Options::.
+
+
+File: diffutils.info-t, Node: Incomplete Lines, Next: Comparing Directories, Prev: Output Formats, Up: Top
+
+3 Incomplete Lines
+******************
+
+When an input file ends in a non-newline character, its last line is
+called an "incomplete line" because its last character is not a newline.
+All other lines are called "full lines" and end in a newline character.
+Incomplete lines do not match full lines unless differences in white
+space are ignored (*note White Space::).
+
+ An incomplete line is normally distinguished on output from a full
+line by a following line that starts with '\'. However, the RCS format
+(*note RCS::) outputs the incomplete line as-is, without any trailing
+newline or following line. The side by side format normally represents
+incomplete lines as-is, but in some cases uses a '\' or '/' gutter
+marker. *Note Side by Side::. The if-then-else line format preserves a
+line's incompleteness with '%L', and discards the newline with '%l'.
+*Note Line Formats::. Finally, with the 'ed' and forward 'ed' output
+formats (*note Output Formats::) 'diff' cannot represent an incomplete
+line, so it pretends there was a newline and reports an error.
+
+ For example, suppose 'F' and 'G' are one-byte files that contain just
+'f' and 'g', respectively. Then 'diff F G' outputs
+
+ 1c1
+ < f
+ \ No newline at end of file
+ ---
+ > g
+ \ No newline at end of file
+
+(The exact message may differ in non-English locales.) 'diff -n F G'
+outputs the following without a trailing newline:
+
+ d1 1
+ a1 1
+ g
+
+'diff -e F G' reports two errors and outputs the following:
+
+ 1c
+ g
+ .
+
+
+File: diffutils.info-t, Node: Comparing Directories, Next: Adjusting Output, Prev: Incomplete Lines, Up: Top
+
+4 Comparing Directories
+***********************
+
+You can use 'diff' to compare some or all of the files in two directory
+trees. When both file name arguments to 'diff' are directories, it
+compares each file that is contained in both directories, examining file
+names in alphabetical order as specified by the 'LC_COLLATE' locale
+category. Normally 'diff' is silent about pairs of files that contain
+no differences, but if you use the '--report-identical-files' ('-s')
+option, it reports pairs of identical files. Normally 'diff' reports
+subdirectories common to both directories without comparing
+subdirectories' files, but if you use the '-r' or '--recursive' option,
+it compares every corresponding pair of files in the directory trees, as
+many levels deep as they go.
+
+ If only one file exists, 'diff' normally does not show its contents;
+it merely reports that one file exists but the other does not. You can
+make 'diff' act as though the missing file is empty, so that it outputs
+the entire contents of the file that actually exists. (It is output as
+either an insertion or a deletion, depending on whether the missing file
+is in the first or the second position.) To do this, use the
+'--new-file' ('-N') option. This option affects command-line arguments
+as well as files found via directory traversal; for example, 'diff -N a
+b' treats 'a' as empty if 'a' does not exist but 'b' does, and similarly
+'diff -N - b' treats standard input as empty if it is closed but 'b'
+exists.
+
+ If the older directory contains large files that are not in the newer
+directory, you can make the patch smaller by using the
+'--unidirectional-new-file' option instead of '-N'. This option is like
+'-N' except that it inserts the contents only of files that appear in
+the second directory but not the first (that is, files that were added).
+At the top of the patch, write instructions for the user applying the
+patch to remove the files that were deleted before applying the patch.
+*Note Making Patches::, for more discussion of making patches for
+distribution.
+
+ To ignore some files while comparing directories, use the
+'--exclude=PATTERN' ('-x PATTERN') option. This option ignores any
+files or subdirectories whose base names match the shell pattern
+PATTERN. Unlike in the shell, a period at the start of the base of a
+file name matches a wildcard at the start of a pattern. You should
+enclose PATTERN in quotes so that the shell does not expand it. For
+example, the option '-x '*.[ao]'' ignores any file whose name ends with
+'.a' or '.o'.
+
+ This option accumulates if you specify it more than once. For
+example, using the options '-x 'RCS' -x '*,v'' ignores any file or
+subdirectory whose base name is 'RCS' or ends with ',v'.
+
+ If you need to give this option many times, you can instead put the
+patterns in a file, one pattern per line, and use the
+'--exclude-from=FILE' ('-X FILE') option. Trailing white space and
+empty lines are ignored in the pattern file.
+
+ If you have been comparing two directories and stopped partway
+through, later you might want to continue where you left off. You can
+do this by using the '--starting-file=FILE' ('-S FILE') option. This
+compares only the file FILE and all alphabetically later files in the
+topmost directory level.
+
+ If two directories differ only in that file names are lower case in
+one directory and upper case in the upper, 'diff' normally reports many
+differences because it compares file names in a case sensitive way.
+With the '--ignore-file-name-case' option, 'diff' ignores case
+differences in file names, so that for example the contents of the file
+'Tao' in one directory are compared to the contents of the file 'TAO' in
+the other. The '--no-ignore-file-name-case' option cancels the effect
+of the '--ignore-file-name-case' option, reverting to the default
+behavior.
+
+ If an '--exclude=PATTERN' ('-x PATTERN') option, or an
+'--exclude-from=FILE' ('-X FILE') option, is specified while the
+'--ignore-file-name-case' option is in effect, case is ignored when
+excluding file names matching the specified patterns.
+
+ To tell 'diff' not to follow a symbolic link, use the
+'--no-dereference' option.
+
+
+File: diffutils.info-t, Node: Adjusting Output, Next: diff Performance, Prev: Comparing Directories, Up: Top
+
+5 Making 'diff' Output Prettier
+*******************************
+
+'diff' provides several ways to adjust the appearance of its output.
+These adjustments can be applied to any output format.
+
+* Menu:
+
+* Tabs:: Preserving the alignment of tab stops.
+* Trailing Blanks:: Suppressing blanks before empty output lines.
+* Pagination:: Page numbering and time-stamping 'diff' output.
+
+
+File: diffutils.info-t, Node: Tabs, Next: Trailing Blanks, Up: Adjusting Output
+
+5.1 Preserving Tab Stop Alignment
+=================================
+
+The lines of text in some of the 'diff' output formats are preceded by
+one or two characters that indicate whether the text is inserted,
+deleted, or changed. The addition of those characters can cause tabs to
+move to the next tab stop, throwing off the alignment of columns in the
+line. GNU 'diff' provides two ways to make tab-aligned columns line up
+correctly.
+
+ The first way is to have 'diff' convert all tabs into the correct
+number of spaces before outputting them; select this method with the
+'--expand-tabs' ('-t') option. To use this form of output with 'patch',
+you must give 'patch' the '-l' or '--ignore-white-space' option (*note
+Changed White Space::, for more information). 'diff' normally assumes
+that tab stops are set every 8 print columns, but this can be altered by
+the '--tabsize=COLUMNS' option.
+
+ The other method for making tabs line up correctly is to add a tab
+character instead of a space after the indicator character at the
+beginning of the line. This ensures that all following tab characters
+are in the same position relative to tab stops that they were in the
+original files, so that the output is aligned correctly. Its
+disadvantage is that it can make long lines too long to fit on one line
+of the screen or the paper. It also does not work with the unified
+output format, which does not have a space character after the change
+type indicator character. Select this method with the '-T' or
+'--initial-tab' option.
+
+
+File: diffutils.info-t, Node: Trailing Blanks, Next: Pagination, Prev: Tabs, Up: Adjusting Output
+
+5.2 Omitting trailing blanks
+============================
+
+When outputting lines in normal or context format, or outputting an
+unchanged line in unified format, 'diff' normally outputs a blank just
+before each line. If the line is empty, the output of 'diff' therefore
+contains trailing blanks even though the input does not contain them.
+For example, when outputting an unchanged empty line in context format,
+'diff' normally outputs a line with two leading spaces.
+
+ Some text editors and email agents routinely delete trailing blanks,
+so it can be a problem to deal with diff output files that contain them.
+You can avoid this problem with the '--suppress-blank-empty' option. It
+causes 'diff' to omit trailing blanks at the end of output lines in
+normal, context, and unified format, unless the trailing blanks were
+already present in the input. This changes the output format slightly,
+so that output lines are guaranteed to never end in a blank unless an
+input line ends in a blank. This format is less likely to be munged by
+text editors or by transmission via email. It is accepted by GNU
+'patch' as well.
+
+
+File: diffutils.info-t, Node: Pagination, Prev: Trailing Blanks, Up: Adjusting Output
+
+5.3 Paginating 'diff' Output
+============================
+
+It can be convenient to have long output page-numbered and time-stamped.
+The '--paginate' ('-l') option does this by sending the 'diff' output
+through the 'pr' program. Here is what the page header might look like
+for 'diff -lc lao tzu':
+
+ 2002-02-22 14:20 diff -lc lao tzu Page 1
+
+
+File: diffutils.info-t, Node: diff Performance, Next: Comparing Three Files, Prev: Adjusting Output, Up: Top
+
+6 'diff' Performance Tradeoffs
+******************************
+
+GNU 'diff' runs quite efficiently; however, in some circumstances you
+can cause it to run faster or produce a more compact set of changes.
+
+ One way to improve 'diff' performance is to use hard or symbolic
+links to files instead of copies. This improves performance because
+'diff' normally does not need to read two hard or symbolic links to the
+same file, since their contents must be identical. For example, suppose
+you copy a large directory hierarchy, make a few changes to the copy,
+and then often use 'diff -r' to compare the original to the copy. If
+the original files are read-only, you can greatly improve performance by
+creating the copy using hard or symbolic links (e.g., with GNU 'cp -lR'
+or 'cp -sR'). Before editing a file in the copy for the first time, you
+should break the link and replace it with a regular copy.
+
+ You can also affect the performance of GNU 'diff' by giving it
+options that change the way it compares files. Performance has more
+than one dimension. These options improve one aspect of performance at
+the cost of another, or they improve performance in some cases while
+hurting it in others.
+
+ The way that GNU 'diff' determines which lines have changed always
+comes up with a near-minimal set of differences. Usually it is good
+enough for practical purposes. If the 'diff' output is large, you might
+want 'diff' to use a modified algorithm that sometimes produces a
+smaller set of differences. The '--minimal' ('-d') option does this;
+however, it can also cause 'diff' to run more slowly than usual, so it
+is not the default behavior.
+
+ When the files you are comparing are large and have small groups of
+changes scattered throughout them, you can use the '--speed-large-files'
+option to make a different modification to the algorithm that 'diff'
+uses. If the input files have a constant small density of changes, this
+option speeds up the comparisons without changing the output. If not,
+'diff' might produce a larger set of differences; however, the output
+will still be correct.
+
+ Normally 'diff' discards the prefix and suffix that is common to both
+files before it attempts to find a minimal set of differences. This
+makes 'diff' run faster, but occasionally it may produce non-minimal
+output. The '--horizon-lines=LINES' option prevents 'diff' from
+discarding the last LINES lines of the prefix and the first LINES lines
+of the suffix. This gives 'diff' further opportunities to find a
+minimal output.
+
+ Suppose a run of changed lines includes a sequence of lines at one
+end and there is an identical sequence of lines just outside the other
+end. The 'diff' command is free to choose which identical sequence is
+included in the hunk. In this case, 'diff' normally shifts the hunk's
+boundaries when this merges adjacent hunks, or shifts a hunk's lines
+towards the end of the file. Merging hunks can make the output look
+nicer in some cases.
+
+
+File: diffutils.info-t, Node: Comparing Three Files, Next: diff3 Merging, Prev: diff Performance, Up: Top
+
+7 Comparing Three Files
+***********************
+
+Use the program 'diff3' to compare three files and show any differences
+among them. ('diff3' can also merge files; see *note diff3 Merging::).
+
+ The "normal" 'diff3' output format shows each hunk of differences
+without surrounding context. Hunks are labeled depending on whether
+they are two-way or three-way, and lines are annotated by their location
+in the input files.
+
+ *Note Invoking diff3::, for more information on how to run 'diff3'.
+
+* Menu:
+
+* Sample diff3 Input:: Sample 'diff3' input for examples.
+* Example diff3 Normal:: Sample output in the normal format.
+* Detailed diff3 Normal:: A detailed description of normal output format.
+* diff3 Hunks:: The format of normal output format.
+
+
+File: diffutils.info-t, Node: Sample diff3 Input, Next: Example diff3 Normal, Up: Comparing Three Files
+
+7.1 A Third Sample Input File
+=============================
+
+Here is a third sample file that will be used in examples to illustrate
+the output of 'diff3' and how various options can change it. The first
+two files are the same that we used for 'diff' (*note Sample diff
+Input::). This is the third sample file, called 'tao':
+
+ The Way that can be told of is not the eternal Way;
+ The name that can be named is not the eternal name.
+ The Nameless is the origin of Heaven and Earth;
+ The named is the mother of all things.
+
+ Therefore let there always be non-being,
+ so we may see their subtlety,
+ And let there always be being,
+ so we may see their result.
+ The two are the same,
+ But after they are produced,
+ they have different names.
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+
+
+File: diffutils.info-t, Node: Example diff3 Normal, Next: Detailed diff3 Normal, Prev: Sample diff3 Input, Up: Comparing Three Files
+
+7.2 An Example of 'diff3' Normal Format
+=======================================
+
+Here is the output of the command 'diff3 lao tzu tao' (*note Sample
+diff3 Input::, for the complete contents of the files). Notice that it
+shows only the lines that are different among the three files.
+
+ ====2
+ 1:1,2c
+ 3:1,2c
+ The Way that can be told of is not the eternal Way;
+ The name that can be named is not the eternal name.
+ 2:0a
+ ====1
+ 1:4c
+ The Named is the mother of all things.
+ 2:2,3c
+ 3:4,5c
+ The named is the mother of all things.
+
+ ====3
+ 1:8c
+ 2:7c
+ so we may see their outcome.
+ 3:9c
+ so we may see their result.
+ ====
+ 1:11a
+ 2:11,13c
+ They both may be called deep and profound.
+ Deeper and more profound,
+ The door of all subtleties!
+ 3:13,14c
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+
+
+File: diffutils.info-t, Node: Detailed diff3 Normal, Next: diff3 Hunks, Prev: Example diff3 Normal, Up: Comparing Three Files
+
+7.3 Detailed Description of 'diff3' Normal Format
+=================================================
+
+Each hunk begins with a line marked '===='. Three-way hunks have plain
+'====' lines, and two-way hunks have '1', '2', or '3' appended to
+specify which of the three input files differ in that hunk. The hunks
+contain copies of two or three sets of input lines each preceded by one
+or two commands identifying where the lines came from.
+
+ Normally, two spaces precede each copy of an input line to
+distinguish it from the commands. But with the '--initial-tab' ('-T')
+option, 'diff3' uses a tab instead of two spaces; this lines up tabs
+correctly. *Note Tabs::, for more information.
+
+ Commands take the following forms:
+
+'FILE:La'
+ This hunk appears after line L of file FILE, and contains no lines
+ in that file. To edit this file to yield the other files, one must
+ append hunk lines taken from the other files. For example, '1:11a'
+ means that the hunk follows line 11 in the first file and contains
+ no lines from that file.
+
+'FILE:Rc'
+ This hunk contains the lines in the range R of file FILE. The
+ range R is a comma-separated pair of line numbers, or just one
+ number if there is only one line. To edit this file to yield the
+ other files, one must change the specified lines to be the lines
+ taken from the other files. For example, '2:11,13c' means that the
+ hunk contains lines 11 through 13 from the second file.
+
+ If the last line in a set of input lines is incomplete (*note
+Incomplete Lines::), it is distinguished on output from a full line by a
+following line that starts with '\'.
+
+
+File: diffutils.info-t, Node: diff3 Hunks, Prev: Detailed diff3 Normal, Up: Comparing Three Files
+
+7.4 'diff3' Hunks
+=================
+
+Groups of lines that differ in two or three of the input files are
+called "diff3 hunks", by analogy with 'diff' hunks (*note Hunks::). If
+all three input files differ in a 'diff3' hunk, the hunk is called a
+"three-way hunk"; if just two input files differ, it is a "two-way
+hunk".
+
+ As with 'diff', several solutions are possible. When comparing the
+files 'A', 'B', and 'C', 'diff3' normally finds 'diff3' hunks by merging
+the two-way hunks output by the two commands 'diff A B' and 'diff A C'.
+This does not necessarily minimize the size of the output, but
+exceptions should be rare.
+
+ For example, suppose 'F' contains the three lines 'a', 'b', 'f', 'G'
+contains the lines 'g', 'b', 'g', and 'H' contains the lines 'a', 'b',
+'h'. 'diff3 F G H' might output the following:
+
+ ====2
+ 1:1c
+ 3:1c
+ a
+ 2:1c
+ g
+ ====
+ 1:3c
+ f
+ 2:3c
+ g
+ 3:3c
+ h
+
+because it found a two-way hunk containing 'a' in the first and third
+files and 'g' in the second file, then the single line 'b' common to all
+three files, then a three-way hunk containing the last line of each
+file.
+
+
+File: diffutils.info-t, Node: diff3 Merging, Next: Interactive Merging, Prev: Comparing Three Files, Up: Top
+
+8 Merging From a Common Ancestor
+********************************
+
+When two people have made changes to copies of the same file, 'diff3'
+can produce a merged output that contains both sets of changes together
+with warnings about conflicts.
+
+ One might imagine programs with names like 'diff4' and 'diff5' to
+compare more than three files simultaneously, but in practice the need
+rarely arises. You can use 'diff3' to merge three or more sets of
+changes to a file by merging two change sets at a time.
+
+ 'diff3' can incorporate changes from two modified versions into a
+common preceding version. This lets you merge the sets of changes
+represented by the two newer files. Specify the common ancestor version
+as the second argument and the two newer versions as the first and third
+arguments, like this:
+
+ diff3 MINE OLDER YOURS
+
+You can remember the order of the arguments by noting that they are in
+alphabetical order.
+
+ You can think of this as subtracting OLDER from YOURS and adding the
+result to MINE, or as merging into MINE the changes that would turn
+OLDER into YOURS. This merging is well-defined as long as MINE and
+OLDER match in the neighborhood of each such change. This fails to be
+true when all three input files differ or when only OLDER differs; we
+call this a "conflict". When all three input files differ, we call the
+conflict an "overlap".
+
+ 'diff3' gives you several ways to handle overlaps and conflicts. You
+can omit overlaps or conflicts, or select only overlaps, or mark
+conflicts with special '<<<<<<<' and '>>>>>>>' lines.
+
+ 'diff3' can output the merge results as an 'ed' script that that can
+be applied to the first file to yield the merged output. However, it is
+usually better to have 'diff3' generate the merged output directly; this
+bypasses some problems with 'ed'.
+
+* Menu:
+
+* Which Changes:: Selecting changes to incorporate.
+* Marking Conflicts:: Marking conflicts.
+* Bypassing ed:: Generating merged output directly.
+* Merging Incomplete Lines:: How 'diff3' merges incomplete lines.
+* Saving the Changed File:: Emulating System V behavior.
+
+
+File: diffutils.info-t, Node: Which Changes, Next: Marking Conflicts, Up: diff3 Merging
+
+8.1 Selecting Which Changes to Incorporate
+==========================================
+
+You can select all unmerged changes from OLDER to YOURS for merging into
+MINE with the '--ed' ('-e') option. You can select only the
+nonoverlapping unmerged changes with '--easy-only' ('-3'), and you can
+select only the overlapping changes with '--overlap-only' ('-x').
+
+ The '-e', '-3' and '-x' options select only "unmerged changes", i.e.
+changes where MINE and YOURS differ; they ignore changes from OLDER to
+YOURS where MINE and YOURS are identical, because they assume that such
+changes have already been merged. If this assumption is not a safe one,
+you can use the '--show-all' ('-A') option (*note Marking Conflicts::).
+
+ Here is the output of the command 'diff3' with each of these three
+options (*note Sample diff3 Input::, for the complete contents of the
+files). Notice that '-e' outputs the union of the disjoint sets of
+changes output by '-3' and '-x'.
+
+ Output of 'diff3 -e lao tzu tao':
+ 11a
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+ .
+ 8c
+ so we may see their result.
+ .
+
+ Output of 'diff3 -3 lao tzu tao':
+ 8c
+ so we may see their result.
+ .
+
+ Output of 'diff3 -x lao tzu tao':
+ 11a
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+ .
+
+
+File: diffutils.info-t, Node: Marking Conflicts, Next: Bypassing ed, Prev: Which Changes, Up: diff3 Merging
+
+8.2 Marking Conflicts
+=====================
+
+'diff3' can mark conflicts in the merged output by bracketing them with
+special marker lines. A conflict that comes from two files A and B is
+marked as follows:
+
+ <<<<<<< A
+ lines from A
+ =======
+ lines from B
+ >>>>>>> B
+
+ A conflict that comes from three files A, B and C is marked as
+follows:
+
+ <<<<<<< A
+ lines from A
+ ||||||| B
+ lines from B
+ =======
+ lines from C
+ >>>>>>> C
+
+ The '--show-all' ('-A') option acts like the '-e' option, except that
+it brackets conflicts, and it outputs all changes from OLDER to YOURS,
+not just the unmerged changes. Thus, given the sample input files
+(*note Sample diff3 Input::), 'diff3 -A lao tzu tao' puts brackets
+around the conflict where only 'tzu' differs:
+
+ <<<<<<< tzu
+ =======
+ The Way that can be told of is not the eternal Way;
+ The name that can be named is not the eternal name.
+ >>>>>>> tao
+
+ And it outputs the three-way conflict as follows:
+
+ <<<<<<< lao
+ ||||||| tzu
+ They both may be called deep and profound.
+ Deeper and more profound,
+ The door of all subtleties!
+ =======
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+ >>>>>>> tao
+
+ The '--show-overlap' ('-E') option outputs less information than the
+'--show-all' ('-A') option, because it outputs only unmerged changes,
+and it never outputs the contents of the second file. Thus the '-E'
+option acts like the '-e' option, except that it brackets the first and
+third files from three-way overlapping changes. Similarly, '-X' acts
+like '-x', except it brackets all its (necessarily overlapping) changes.
+For example, for the three-way overlapping change above, the '-E' and
+'-X' options output the following:
+
+ <<<<<<< lao
+ =======
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+ >>>>>>> tao
+
+ If you are comparing files that have meaningless or uninformative
+names, you can use the '--label=LABEL' option to show alternate names in
+the '<<<<<<<', '|||||||' and '>>>>>>>' brackets. This option can be
+given up to three times, once for each input file. Thus 'diff3 -A
+--label X --label Y --label Z A B C' acts like 'diff3 -A A B C', except
+that the output looks like it came from files named 'X', 'Y' and 'Z'
+rather than from files named 'A', 'B' and 'C'.
+
+
+File: diffutils.info-t, Node: Bypassing ed, Next: Merging Incomplete Lines, Prev: Marking Conflicts, Up: diff3 Merging
+
+8.3 Generating the Merged Output Directly
+=========================================
+
+With the '--merge' ('-m') option, 'diff3' outputs the merged file
+directly. This is more efficient than using 'ed' to generate it, and
+works even with non-text files that 'ed' would reject. If you specify
+'-m' without an 'ed' script option, '-A' is assumed.
+
+ For example, the command 'diff3 -m lao tzu tao' (*note Sample diff3
+Input:: for a copy of the input files) would output the following:
+
+ <<<<<<< tzu
+ =======
+ The Way that can be told of is not the eternal Way;
+ The name that can be named is not the eternal name.
+ >>>>>>> tao
+ The Nameless is the origin of Heaven and Earth;
+ The Named is the mother of all things.
+ Therefore let there always be non-being,
+ so we may see their subtlety,
+ And let there always be being,
+ so we may see their result.
+ The two are the same,
+ But after they are produced,
+ they have different names.
+ <<<<<<< lao
+ ||||||| tzu
+ They both may be called deep and profound.
+ Deeper and more profound,
+ The door of all subtleties!
+ =======
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+ >>>>>>> tao
+
+
+File: diffutils.info-t, Node: Merging Incomplete Lines, Next: Saving the Changed File, Prev: Bypassing ed, Up: diff3 Merging
+
+8.4 How 'diff3' Merges Incomplete Lines
+=======================================
+
+With '-m', incomplete lines (*note Incomplete Lines::) are simply copied
+to the output as they are found; if the merged output ends in an
+conflict and one of the input files ends in an incomplete line,
+succeeding '|||||||', '=======' or '>>>>>>>' brackets appear somewhere
+other than the start of a line because they are appended to the
+incomplete line.
+
+ Without '-m', if an 'ed' script option is specified and an incomplete
+line is found, 'diff3' generates a warning and acts as if a newline had
+been present.
+
+
+File: diffutils.info-t, Node: Saving the Changed File, Prev: Merging Incomplete Lines, Up: diff3 Merging
+
+8.5 Saving the Changed File
+===========================
+
+Traditional Unix 'diff3' generates an 'ed' script without the trailing
+'w' and 'q' commands that save the changes. System V 'diff3' generates
+these extra commands. GNU 'diff3' normally behaves like traditional
+Unix 'diff3', but with the '-i' option it behaves like System V 'diff3'
+and appends the 'w' and 'q' commands.
+
+ The '-i' option requires one of the 'ed' script options '-AeExX3',
+and is incompatible with the merged output option '-m'.
+
+
+File: diffutils.info-t, Node: Interactive Merging, Next: Merging with patch, Prev: diff3 Merging, Up: Top
+
+9 Interactive Merging with 'sdiff'
+**********************************
+
+With 'sdiff', you can merge two files interactively based on a
+side-by-side '-y' format comparison (*note Side by Side::). Use
+'--output=FILE' ('-o FILE') to specify where to put the merged text.
+*Note Invoking sdiff::, for more details on the options to 'sdiff'.
+
+ Another way to merge files interactively is to use the Emacs Lisp
+package 'emerge'. *Note Emerge: (emacs)Emerge, for more information.
+
+* Menu:
+
+* sdiff Option Summary:: Summary of 'sdiff' options.
+* Merge Commands:: Merging two files interactively.
+
+
+File: diffutils.info-t, Node: sdiff Option Summary, Next: Merge Commands, Up: Interactive Merging
+
+9.1 Specifying 'diff' Options to 'sdiff'
+========================================
+
+The following 'sdiff' options have the same meaning as for 'diff'.
+*Note diff Options::, for the use of these options.
+
+ -a -b -d -i -t -v
+ -B -E -I REGEXP -Z
+
+ --expand-tabs
+ --ignore-blank-lines --ignore-case
+ --ignore-matching-lines=REGEXP --ignore-space-change
+ --ignore-tab-expansion --ignore-trailing-space
+ --left-column --minimal --speed-large-files
+ --strip-trailing-cr --suppress-common-lines
+ --tabsize=COLUMNS --text --version --width=COLUMNS
+
+ For historical reasons, 'sdiff' has alternate names for some options.
+The '-l' option is equivalent to the '--left-column' option, and
+similarly '-s' is equivalent to '--suppress-common-lines'. The meaning
+of the 'sdiff' '-w' and '-W' options is interchanged from that of
+'diff': with 'sdiff', '-w COLUMNS' is equivalent to '--width=COLUMNS',
+and '-W' is equivalent to '--ignore-all-space'. 'sdiff' without the
+'-o' option is equivalent to 'diff' with the '--side-by-side' ('-y')
+option (*note Side by Side::).
+
+
+File: diffutils.info-t, Node: Merge Commands, Prev: sdiff Option Summary, Up: Interactive Merging
+
+9.2 Merge Commands
+==================
+
+Groups of common lines, with a blank gutter, are copied from the first
+file to the output. After each group of differing lines, 'sdiff'
+prompts with '%' and pauses, waiting for one of the following commands.
+Follow each command with <RET>.
+
+'e'
+ Discard both versions. Invoke a text editor on an empty temporary
+ file, then copy the resulting file to the output.
+
+'eb'
+ Concatenate the two versions, edit the result in a temporary file,
+ then copy the edited result to the output.
+
+'ed'
+ Like 'eb', except precede each version with a header that shows
+ what file and lines the version came from.
+
+'el'
+'e1'
+ Edit a copy of the left version, then copy the result to the
+ output.
+
+'er'
+'e2'
+ Edit a copy of the right version, then copy the result to the
+ output.
+
+'l'
+'1'
+ Copy the left version to the output.
+
+'q'
+ Quit.
+
+'r'
+'2'
+ Copy the right version to the output.
+
+'s'
+ Silently copy common lines.
+
+'v'
+ Verbosely copy common lines. This is the default.
+
+ The text editor invoked is specified by the 'EDITOR' environment
+variable if it is set. The default is system-dependent.
+
+
+File: diffutils.info-t, Node: Merging with patch, Next: Making Patches, Prev: Interactive Merging, Up: Top
+
+10 Merging with 'patch'
+***********************
+
+'patch' takes comparison output produced by 'diff' and applies the
+differences to a copy of the original file, producing a patched version.
+With 'patch', you can distribute just the changes to a set of files
+instead of distributing the entire file set; your correspondents can
+apply 'patch' to update their copy of the files with your changes.
+'patch' automatically determines the diff format, skips any leading or
+trailing headers, and uses the headers to determine which file to patch.
+This lets your correspondents feed a mail message containing a
+difference listing directly to 'patch'.
+
+ 'patch' detects and warns about common problems like forward patches.
+It saves any patches that it could not apply. It can also maintain a
+'patchlevel.h' file to ensure that your correspondents apply diffs in
+the proper order.
+
+ 'patch' accepts a series of diffs in its standard input, usually
+separated by headers that specify which file to patch. It applies
+'diff' hunks (*note Hunks::) one by one. If a hunk does not exactly
+match the original file, 'patch' uses heuristics to try to patch the
+file as well as it can. If no approximate match can be found, 'patch'
+rejects the hunk and skips to the next hunk. 'patch' normally replaces
+each file F with its new version, putting reject hunks (if any) into
+'F.rej'.
+
+ *Note Invoking patch::, for detailed information on the options to
+'patch'.
+
+* Menu:
+
+* patch Input:: Selecting the type of 'patch' input.
+* Revision Control:: Getting files from RCS, SCCS, etc.
+* Imperfect:: Dealing with imperfect patches.
+* Creating and Removing:: Creating and removing files with a patch.
+* Patching Time Stamps:: Updating time stamps on patched files.
+* Multiple Patches:: Handling multiple patches in a file.
+* patch Directories:: Changing directory and stripping directories.
+* Backups:: Whether backup files are made.
+* Backup Names:: Backup file names.
+* Reject Names:: Reject file names.
+* patch Messages:: Messages and questions 'patch' can produce.
+* patch and POSIX:: Conformance to the POSIX standard.
+* patch and Tradition:: GNU versus traditional 'patch'.
+
+
+File: diffutils.info-t, Node: patch Input, Next: Revision Control, Up: Merging with patch
+
+10.1 Selecting the 'patch' Input Format
+=======================================
+
+'patch' normally determines which 'diff' format the patch file uses by
+examining its contents. For patch files that contain particularly
+confusing leading text, you might need to use one of the following
+options to force 'patch' to interpret the patch file as a certain format
+of diff. The output formats listed here are the only ones that 'patch'
+can understand.
+
+'-c'
+'--context'
+ context diff.
+
+'-e'
+'--ed'
+ 'ed' script.
+
+'-n'
+'--normal'
+ normal diff.
+
+'-u'
+'--unified'
+ unified diff.
+
+
+File: diffutils.info-t, Node: Revision Control, Next: Imperfect, Prev: patch Input, Up: Merging with patch
+
+10.2 Revision Control
+=====================
+
+If a nonexistent input file is under a revision control system supported
+by 'patch', 'patch' normally asks the user whether to get (or check out)
+the file from the revision control system. Patch currently supports
+RCS, ClearCase and SCCS. Under RCS and SCCS, 'patch' also asks when the
+input file is read-only and matches the default version in the revision
+control system.
+
+ The '--get=NUM' ('-g NUM') option affects access to files under
+supported revision control systems. If NUM is positive, 'patch' gets
+the file without asking the user; if zero, 'patch' neither asks the user
+nor gets the file; and if negative, 'patch' asks the user before getting
+the file. The default value of NUM is given by the value of the
+'PATCH_GET' environment variable if it is set; if not, the default value
+is zero if 'patch' is conforming to POSIX, negative otherwise. *Note
+patch and POSIX::.
+
+ The choice of revision control system is unaffected by the
+'VERSION_CONTROL' environment variable (*note Backup Names::).
+
+
+File: diffutils.info-t, Node: Imperfect, Next: Creating and Removing, Prev: Revision Control, Up: Merging with patch
+
+10.3 Applying Imperfect Patches
+===============================
+
+'patch' tries to skip any leading text in the patch file, apply the
+diff, and then skip any trailing text. Thus you can feed a mail message
+directly to 'patch', and it should work. If the entire diff is indented
+by a constant amount of white space, 'patch' automatically ignores the
+indentation. If a context diff contains trailing carriage return on
+each line, 'patch' automatically ignores the carriage return. If a
+context diff has been encapsulated by prepending '- ' to lines beginning
+with '-' as per Internet RFC 934
+(ftp://ftp.isi.edu/in-notes/rfc934.txt), 'patch' automatically
+unencapsulates the input.
+
+ However, certain other types of imperfect input require user
+intervention or testing.
+
+* Menu:
+
+* Changed White Space:: When tabs and spaces don't match exactly.
+* Reversed Patches:: Applying reversed patches correctly.
+* Inexact:: Helping 'patch' find close matches.
+* Dry Runs:: Predicting what 'patch' will do.
+
+
+File: diffutils.info-t, Node: Changed White Space, Next: Reversed Patches, Up: Imperfect
+
+10.3.1 Applying Patches with Changed White Space
+------------------------------------------------
+
+Sometimes mailers, editors, or other programs change spaces into tabs,
+or vice versa. If this happens to a patch file or an input file, the
+files might look the same, but 'patch' will not be able to match them
+properly. If this problem occurs, use the '-l' or
+'--ignore-white-space' option, which makes 'patch' compare blank
+characters (i.e. spaces and tabs) loosely so that any nonempty sequence
+of blanks in the patch file matches any nonempty sequence of blanks in
+the input files. Non-blank characters must still match exactly. Each
+line of the context must still match a line in the input file.
+
+
+File: diffutils.info-t, Node: Reversed Patches, Next: Inexact, Prev: Changed White Space, Up: Imperfect
+
+10.3.2 Applying Reversed Patches
+--------------------------------
+
+Sometimes people run 'diff' with the new file first instead of second.
+This creates a diff that is "reversed". To apply such patches, give
+'patch' the '--reverse' ('-R') option. 'patch' then attempts to swap
+each hunk around before applying it. Rejects come out in the swapped
+format.
+
+ Often 'patch' can guess that the patch is reversed. If the first
+hunk of a patch fails, 'patch' reverses the hunk to see if it can apply
+it that way. If it can, 'patch' asks you if you want to have the '-R'
+option set; if it can't, 'patch' continues to apply the patch normally.
+This method cannot detect a reversed patch if it is a normal diff and
+the first command is an append (which should have been a delete) since
+appends always succeed, because a null context matches anywhere. But
+most patches add or change lines rather than delete them, so most
+reversed normal diffs begin with a delete, which fails, and 'patch'
+notices.
+
+ If you apply a patch that you have already applied, 'patch' thinks it
+is a reversed patch and offers to un-apply the patch. This could be
+construed as a feature. If you did this inadvertently and you don't
+want to un-apply the patch, just answer 'n' to this offer and to the
+subsequent "apply anyway" question--or type 'C-c' to kill the 'patch'
+process.
+
+
+File: diffutils.info-t, Node: Inexact, Next: Dry Runs, Prev: Reversed Patches, Up: Imperfect
+
+10.3.3 Helping 'patch' Find Inexact Matches
+-------------------------------------------
+
+For context diffs, and to a lesser extent normal diffs, 'patch' can
+detect when the line numbers mentioned in the patch are incorrect, and
+it attempts to find the correct place to apply each hunk of the patch.
+As a first guess, it takes the line number mentioned in the hunk, plus
+or minus any offset used in applying the previous hunk. If that is not
+the correct place, 'patch' scans both forward and backward for a set of
+lines matching the context given in the hunk.
+
+ First 'patch' looks for a place where all lines of the context match.
+If it cannot find such a place, and it is reading a context or unified
+diff, and the maximum fuzz factor is set to 1 or more, then 'patch'
+makes another scan, ignoring the first and last line of context. If
+that fails, and the maximum fuzz factor is set to 2 or more, it makes
+another scan, ignoring the first two and last two lines of context are
+ignored. It continues similarly if the maximum fuzz factor is larger.
+
+ The '--fuzz=LINES' ('-F LINES') option sets the maximum fuzz factor
+to LINES. This option only applies to context and unified diffs; it
+ignores up to LINES lines while looking for the place to install a hunk.
+Note that a larger fuzz factor increases the odds of making a faulty
+patch. The default fuzz factor is 2; there is no point to setting it to
+more than the number of lines of context in the diff, ordinarily 3.
+
+ If 'patch' cannot find a place to install a hunk of the patch, it
+writes the hunk out to a reject file (*note Reject Names::, for
+information on how reject files are named). It writes out rejected
+hunks in context format no matter what form the input patch is in. If
+the input is a normal or 'ed' diff, many of the contexts are simply
+null. The line numbers on the hunks in the reject file may be different
+from those in the patch file: they show the approximate location where
+'patch' thinks the failed hunks belong in the new file rather than in
+the old one.
+
+ If the '--verbose' option is given, then as it completes each hunk
+'patch' tells you whether the hunk succeeded or failed, and if it
+failed, on which line (in the new file) 'patch' thinks the hunk should
+go. If this is different from the line number specified in the diff, it
+tells you the offset. A single large offset _may_ indicate that 'patch'
+installed a hunk in the wrong place. 'patch' also tells you if it used
+a fuzz factor to make the match, in which case you should also be
+slightly suspicious.
+
+ 'patch' cannot tell if the line numbers are off in an 'ed' script,
+and can only detect wrong line numbers in a normal diff when it finds a
+change or delete command. It may have the same problem with a context
+diff using a fuzz factor equal to or greater than the number of lines of
+context shown in the diff (typically 3). In these cases, you should
+probably look at a context diff between your original and patched input
+files to see if the changes make sense. Compiling without errors is a
+pretty good indication that the patch worked, but not a guarantee.
+
+ A patch against an empty file applies to a nonexistent file, and vice
+versa. *Note Creating and Removing::.
+
+ 'patch' usually produces the correct results, even when it must make
+many guesses. However, the results are guaranteed only when the patch
+is applied to an exact copy of the file that the patch was generated
+from.
+
+
+File: diffutils.info-t, Node: Dry Runs, Prev: Inexact, Up: Imperfect
+
+10.3.4 Predicting what 'patch' will do
+--------------------------------------
+
+It may not be obvious in advance what 'patch' will do with a complicated
+or poorly formatted patch. If you are concerned that the input might
+cause 'patch' to modify the wrong files, you can use the '--dry-run'
+option, which causes 'patch' to print the results of applying patches
+without actually changing any files. You can then inspect the
+diagnostics generated by the dry run to see whether 'patch' will modify
+the files that you expect. If the patch does not do what you want, you
+can modify the patch (or the other options to 'patch') and try another
+dry run. Once you are satisfied with the proposed patch you can apply
+it by invoking 'patch' as before, but this time without the '--dry-run'
+option.
+
+
+File: diffutils.info-t, Node: Creating and Removing, Next: Patching Time Stamps, Prev: Imperfect, Up: Merging with patch
+
+10.4 Creating and Removing Files
+================================
+
+Sometimes when comparing two directories, a file may exist in one
+directory but not the other. If you give 'diff' the '--new-file' ('-N')
+option, or if you supply an old or new file that is named '/dev/null' or
+is empty and is dated the Epoch (1970-01-01 00:00:00 UTC), 'diff'
+outputs a patch that adds or deletes the contents of this file. When
+given such a patch, 'patch' normally creates a new file or removes the
+old file. However, when conforming to POSIX (*note patch and POSIX::),
+'patch' does not remove the old file, but leaves it empty. The
+'--remove-empty-files' ('-E') option causes 'patch' to remove output
+files that are empty after applying a patch, even if the patch does not
+appear to be one that removed the file.
+
+ If the patch appears to create a file that already exists, 'patch'
+asks for confirmation before applying the patch.
+
+
+File: diffutils.info-t, Node: Patching Time Stamps, Next: Multiple Patches, Prev: Creating and Removing, Up: Merging with patch
+
+10.5 Updating Time Stamps on Patched Files
+==========================================
+
+When 'patch' updates a file, it normally sets the file's last-modified
+time stamp to the current time of day. If you are using 'patch' to
+track a software distribution, this can cause 'make' to incorrectly
+conclude that a patched file is out of date. For example, if 'syntax.c'
+depends on 'syntax.y', and 'patch' updates 'syntax.c' and then
+'syntax.y', then 'syntax.c' will normally appear to be out of date with
+respect to 'syntax.y' even though its contents are actually up to date.
+
+ The '--set-utc' ('-Z') option causes 'patch' to set a patched file's
+modification and access times to the time stamps given in context diff
+headers. If the context diff headers do not specify a time zone, they
+are assumed to use Coordinated Universal Time (UTC, often known as GMT).
+
+ The '--set-time' ('-T') option acts like '-Z' or '--set-utc', except
+that it assumes that the context diff headers' time stamps use local
+time instead of UTC. This option is not recommended, because patches
+using local time cannot easily be used by people in other time zones,
+and because local time stamps are ambiguous when local clocks move
+backwards during daylight-saving time adjustments. If the context diff
+headers specify a time zone, this option is equivalent to '--set-utc'
+('-Z').
+
+ 'patch' normally refrains from setting a file's time stamps if the
+file's original last-modified time stamp does not match the time given
+in the diff header, of if the file's contents do not exactly match the
+patch. However, if the '--force' ('-f') option is given, the file's
+time stamps are set regardless.
+
+ Due to the limitations of the current 'diff' format, 'patch' cannot
+update the times of files whose contents have not changed. Also, if you
+set file time stamps to values other than the current time of day, you
+should also remove (e.g., with 'make clean') all files that depend on
+the patched files, so that later invocations of 'make' do not get
+confused by the patched files' times.
+
+
+File: diffutils.info-t, Node: Multiple Patches, Next: patch Directories, Prev: Patching Time Stamps, Up: Merging with patch
+
+10.6 Multiple Patches in a File
+===============================
+
+If the patch file contains more than one patch, and if you do not
+specify an input file on the command line, 'patch' tries to apply each
+patch as if they came from separate patch files. This means that it
+determines the name of the file to patch for each patch, and that it
+examines the leading text before each patch for file names and
+prerequisite revision level (*note Making Patches::, for more on that
+topic).
+
+ 'patch' uses the following rules to intuit a file name from the
+leading text before a patch. First, 'patch' takes an ordered list of
+candidate file names as follows:
+
+ * If the header is that of a context diff, 'patch' takes the old and
+ new file names in the header. A name is ignored if it does not
+ have enough slashes to satisfy the '-pNUM' or '--strip=NUM' option.
+ The name '/dev/null' is also ignored.
+
+ * If there is an 'Index:' line in the leading garbage and if either
+ the old and new names are both absent or if 'patch' is conforming
+ to POSIX, 'patch' takes the name in the 'Index:' line.
+
+ * For the purpose of the following rules, the candidate file names
+ are considered to be in the order (old, new, index), regardless of
+ the order that they appear in the header.
+
+Then 'patch' selects a file name from the candidate list as follows:
+
+ * If some of the named files exist, 'patch' selects the first name if
+ conforming to POSIX, and the best name otherwise.
+
+ * If 'patch' is not ignoring RCS, ClearCase, and SCCS (*note Revision
+ Control::), and no named files exist but an RCS, ClearCase, or SCCS
+ master is found, 'patch' selects the first named file with an RCS,
+ ClearCase, or SCCS master.
+
+ * If no named files exist, no RCS, ClearCase, or SCCS master was
+ found, some names are given, 'patch' is not conforming to POSIX,
+ and the patch appears to create a file, 'patch' selects the best
+ name requiring the creation of the fewest directories.
+
+ * If no file name results from the above heuristics, you are asked
+ for the name of the file to patch, and 'patch' selects that name.
+
+ To determine the "best" of a nonempty list of file names, 'patch'
+first takes all the names with the fewest path name components; of
+those, it then takes all the names with the shortest basename; of those,
+it then takes all the shortest names; finally, it takes the first
+remaining name.
+
+ *Note patch and POSIX::, to see whether 'patch' is conforming to
+POSIX.
+
+
+File: diffutils.info-t, Node: patch Directories, Next: Backups, Prev: Multiple Patches, Up: Merging with patch
+
+10.7 Applying Patches in Other Directories
+==========================================
+
+The '--directory=DIRECTORY' ('-d DIRECTORY') option to 'patch' makes
+directory DIRECTORY the current directory for interpreting both file
+names in the patch file, and file names given as arguments to other
+options (such as '-B' and '-o'). For example, while in a mail reading
+program, you can patch a file in the '/usr/src/emacs' directory directly
+from a message containing the patch like this:
+
+ | patch -d /usr/src/emacs
+
+ Sometimes the file names given in a patch contain leading
+directories, but you keep your files in a directory different from the
+one given in the patch. In those cases, you can use the
+'--strip=NUMBER' ('-pNUMBER') option to set the file name strip count to
+NUMBER. The strip count tells 'patch' how many slashes, along with the
+directory names between them, to strip from the front of file names. A
+sequence of one or more adjacent slashes is counted as a single slash.
+By default, 'patch' strips off all leading directories, leaving just the
+base file names.
+
+ For example, suppose the file name in the patch file is
+'/gnu/src/emacs/etc/NEWS'. Using '-p0' gives the entire file name
+unmodified, '-p1' gives 'gnu/src/emacs/etc/NEWS' (no leading slash),
+'-p4' gives 'etc/NEWS', and not specifying '-p' at all gives 'NEWS'.
+
+ 'patch' looks for each file (after any slashes have been stripped) in
+the current directory, or if you used the '-d DIRECTORY' option, in that
+directory.
+
+
+File: diffutils.info-t, Node: Backups, Next: Backup Names, Prev: patch Directories, Up: Merging with patch
+
+10.8 Backup Files
+=================
+
+Normally, 'patch' creates a backup file if the patch does not exactly
+match the original input file, because in that case the original data
+might not be recovered if you undo the patch with 'patch -R' (*note
+Reversed Patches::). However, when conforming to POSIX, 'patch' does
+not create backup files by default. *Note patch and POSIX::.
+
+ The '--backup' ('-b') option causes 'patch' to make a backup file
+regardless of whether the patch matches the original input. The
+'--backup-if-mismatch' option causes 'patch' to create backup files for
+mismatches files; this is the default when not conforming to POSIX. The
+'--no-backup-if-mismatch' option causes 'patch' to not create backup
+files, even for mismatched patches; this is the default when conforming
+to POSIX.
+
+ When backing up a file that does not exist, an empty, unreadable
+backup file is created as a placeholder to represent the nonexistent
+file.
+
+
+File: diffutils.info-t, Node: Backup Names, Next: Reject Names, Prev: Backups, Up: Merging with patch
+
+10.9 Backup File Names
+======================
+
+Normally, 'patch' renames an original input file into a backup file by
+appending to its name the extension '.orig', or '~' if using '.orig'
+would make the backup file name too long.(1) The '-z BACKUP-SUFFIX' or
+'--suffix=BACKUP-SUFFIX' option causes 'patch' to use BACKUP-SUFFIX as
+the backup extension instead.
+
+ Alternately, you can specify the extension for backup files with the
+'SIMPLE_BACKUP_SUFFIX' environment variable, which the options override.
+
+ 'patch' can also create numbered backup files the way GNU Emacs does.
+With this method, instead of having a single backup of each file,
+'patch' makes a new backup file name each time it patches a file. For
+example, the backups of a file named 'sink' would be called,
+successively, 'sink.~1~', 'sink.~2~', 'sink.~3~', etc.
+
+ The '-V BACKUP-STYLE' or '--version-control=BACKUP-STYLE' option
+takes as an argument a method for creating backup file names. You can
+alternately control the type of backups that 'patch' makes with the
+'PATCH_VERSION_CONTROL' environment variable, which the '-V' option
+overrides. If 'PATCH_VERSION_CONTROL' is not set, the 'VERSION_CONTROL'
+environment variable is used instead. Please note that these options
+and variables control backup file names; they do not affect the choice
+of revision control system (*note Revision Control::).
+
+ The values of these environment variables and the argument to the
+'-V' option are like the GNU Emacs 'version-control' variable (*note
+(emacs)Backup Names::, for more information on backup versions in
+Emacs). They also recognize synonyms that are more descriptive. The
+valid values are listed below; unique abbreviations are acceptable.
+
+'t'
+'numbered'
+ Always make numbered backups.
+
+'nil'
+'existing'
+ Make numbered backups of files that already have them, simple
+ backups of the others. This is the default.
+
+'never'
+'simple'
+ Always make simple backups.
+
+ You can also tell 'patch' to prepend a prefix, such as a directory
+name, to produce backup file names. The '--prefix=PREFIX' ('-B PREFIX')
+option makes backup files by prepending PREFIX to them. The
+'--basename-prefix=PREFIX' ('-Y PREFIX') prepends PREFIX to the last
+file name component of backup file names instead; for example, '-Y ~'
+causes the backup name for 'dir/file.c' to be 'dir/~file.c'. If you use
+either of these prefix options, the suffix-based options are ignored.
+
+ If you specify the output file with the '-o' option, that file is the
+one that is backed up, not the input file.
+
+ Options that affect the names of backup files do not affect whether
+backups are made. For example, if you specify the
+'--no-backup-if-mismatch' option, none of the options described in this
+section have any affect, because no backups are made.
+
+ ---------- Footnotes ----------
+
+ (1) A coding error in GNU 'patch' version 2.5.4 causes it to always
+use '~', but this should be fixed in the next release.
+
+
+File: diffutils.info-t, Node: Reject Names, Next: patch Messages, Prev: Backup Names, Up: Merging with patch
+
+10.10 Reject File Names
+=======================
+
+The names for reject files (files containing patches that 'patch' could
+not find a place to apply) are normally the name of the output file with
+'.rej' appended (or '#' if using '.rej' would make the backup file name
+too long).
+
+ Alternatively, you can tell 'patch' to place all of the rejected
+patches in a single file. The '-r REJECT-FILE' or
+'--reject-file=REJECT-FILE' option uses REJECT-FILE as the reject file
+name.
+
+
+File: diffutils.info-t, Node: patch Messages, Next: patch and POSIX, Prev: Reject Names, Up: Merging with patch
+
+10.11 Messages and Questions from 'patch'
+=========================================
+
+'patch' can produce a variety of messages, especially if it has trouble
+decoding its input. In a few situations where it's not sure how to
+proceed, 'patch' normally prompts you for more information from the
+keyboard. There are options to produce more or fewer messages, to have
+it not ask for keyboard input, and to affect the way that file names are
+quoted in messages.
+
+* Menu:
+
+* More or Fewer Messages:: Controlling the verbosity of 'patch'.
+* patch and Keyboard Input:: Inhibiting keyboard input.
+* patch Quoting Style:: Quoting file names in diagnostics.
+
+ 'patch' exits with status 0 if all hunks are applied successfully, 1
+if some hunks cannot be applied, and 2 if there is more serious trouble.
+When applying a set of patches in a loop, you should check the exit
+status, so you don't apply a later patch to a partially patched file.
+
+
+File: diffutils.info-t, Node: More or Fewer Messages, Next: patch and Keyboard Input, Up: patch Messages
+
+10.11.1 Controlling the Verbosity of 'patch'
+--------------------------------------------
+
+You can cause 'patch' to produce more messages by using the '--verbose'
+option. For example, when you give this option, the message 'Hmm...'
+indicates that 'patch' is reading text in the patch file, attempting to
+determine whether there is a patch in that text, and if so, what kind of
+patch it is.
+
+ You can inhibit all terminal output from 'patch', unless an error
+occurs, by using the '-s', '--quiet', or '--silent' option.
+
+
+File: diffutils.info-t, Node: patch and Keyboard Input, Next: patch Quoting Style, Prev: More or Fewer Messages, Up: patch Messages
+
+10.11.2 Inhibiting Keyboard Input
+---------------------------------
+
+There are two ways you can prevent 'patch' from asking you any
+questions. The '--force' ('-f') option assumes that you know what you
+are doing. It causes 'patch' to do the following:
+
+ * Skip patches that do not contain file names in their headers.
+
+ * Patch files even though they have the wrong version for the
+ 'Prereq:' line in the patch;
+
+ * Assume that patches are not reversed even if they look like they
+ are.
+
+The '--batch' ('-t') option is similar to '-f', in that it suppresses
+questions, but it makes somewhat different assumptions:
+
+ * Skip patches that do not contain file names in their headers (the
+ same as '-f').
+
+ * Skip patches for which the file has the wrong version for the
+ 'Prereq:' line in the patch;
+
+ * Assume that patches are reversed if they look like they are.
+
+
+File: diffutils.info-t, Node: patch Quoting Style, Prev: patch and Keyboard Input, Up: patch Messages
+
+10.11.3 'patch' Quoting Style
+-----------------------------
+
+When 'patch' outputs a file name in a diagnostic message, it can format
+the name in any of several ways. This can be useful to output file
+names unambiguously, even if they contain punctuation or special
+characters like newlines. The '--quoting-style=WORD' option controls
+how names are output. The WORD should be one of the following:
+
+'literal'
+ Output names as-is.
+'shell'
+ Quote names for the shell if they contain shell metacharacters or
+ would cause ambiguous output.
+'shell-always'
+ Quote names for the shell, even if they would normally not require
+ quoting.
+'c'
+ Quote names as for a C language string.
+'escape'
+ Quote as with 'c' except omit the surrounding double-quote
+ characters.
+
+ You can specify the default value of the '--quoting-style' option
+with the environment variable 'QUOTING_STYLE'. If that environment
+variable is not set, the default value is 'shell', but this default may
+change in a future version of 'patch'.
+
+
+File: diffutils.info-t, Node: patch and POSIX, Next: patch and Tradition, Prev: patch Messages, Up: Merging with patch
+
+10.12 'patch' and the POSIX Standard
+====================================
+
+If you specify the '--posix' option, or set the 'POSIXLY_CORRECT'
+environment variable, 'patch' conforms more strictly to the POSIX
+standard, as follows:
+
+ * Take the first existing file from the list (old, new, index) when
+ intuiting file names from diff headers. *Note Multiple Patches::.
+
+ * Do not remove files that are removed by a diff. *Note Creating and
+ Removing::.
+
+ * Do not ask whether to get files from RCS, ClearCase, or SCCS.
+ *Note Revision Control::.
+
+ * Require that all options precede the files in the command line.
+
+ * Do not backup files, even when there is a mismatch. *Note
+ Backups::.
+
+
+File: diffutils.info-t, Node: patch and Tradition, Prev: patch and POSIX, Up: Merging with patch
+
+10.13 GNU 'patch' and Traditional 'patch'
+=========================================
+
+The current version of GNU 'patch' normally follows the POSIX standard.
+*Note patch and POSIX::, for the few exceptions to this general rule.
+
+ Unfortunately, POSIX redefined the behavior of 'patch' in several
+important ways. You should be aware of the following differences if you
+must interoperate with traditional 'patch', or with GNU 'patch' version
+2.1 and earlier.
+
+ * In traditional 'patch', the '-p' option's operand was optional, and
+ a bare '-p' was equivalent to '-p0'. The '-p' option now requires
+ an operand, and '-p 0' is now equivalent to '-p0'. For maximum
+ compatibility, use options like '-p0' and '-p1'.
+
+ Also, traditional 'patch' simply counted slashes when stripping
+ path prefixes; 'patch' now counts pathname components. That is, a
+ sequence of one or more adjacent slashes now counts as a single
+ slash. For maximum portability, avoid sending patches containing
+ '//' in file names.
+
+ * In traditional 'patch', backups were enabled by default. This
+ behavior is now enabled with the '--backup' ('-b') option.
+
+ Conversely, in POSIX 'patch', backups are never made, even when
+ there is a mismatch. In GNU 'patch', this behavior is enabled with
+ the '--no-backup-if-mismatch' option, or by conforming to POSIX.
+
+ The '-b SUFFIX' option of traditional 'patch' is equivalent to the
+ '-b -z SUFFIX' options of GNU 'patch'.
+
+ * Traditional 'patch' used a complicated (and incompletely
+ documented) method to intuit the name of the file to be patched
+ from the patch header. This method did not conform to POSIX, and
+ had a few gotchas. Now 'patch' uses a different, equally
+ complicated (but better documented) method that is optionally
+ POSIX-conforming; we hope it has fewer gotchas. The two methods
+ are compatible if the file names in the context diff header and the
+ 'Index:' line are all identical after prefix-stripping. Your patch
+ is normally compatible if each header's file names all contain the
+ same number of slashes.
+
+ * When traditional 'patch' asked the user a question, it sent the
+ question to standard error and looked for an answer from the first
+ file in the following list that was a terminal: standard error,
+ standard output, '/dev/tty', and standard input. Now 'patch' sends
+ questions to standard output and gets answers from '/dev/tty'.
+ Defaults for some answers have been changed so that 'patch' never
+ goes into an infinite loop when using default answers.
+
+ * Traditional 'patch' exited with a status value that counted the
+ number of bad hunks, or with status 1 if there was real trouble.
+ Now 'patch' exits with status 1 if some hunks failed, or with 2 if
+ there was real trouble.
+
+ * Limit yourself to the following options when sending instructions
+ meant to be executed by anyone running GNU 'patch', traditional
+ 'patch', or a 'patch' that conforms to POSIX. Spaces are
+ significant in the following list, and operands are required.
+
+ -c
+ -d DIR
+ -D DEFINE
+ -e
+ -l
+ -n
+ -N
+ -o OUTFILE
+ -pNUM
+ -R
+ -r REJECTFILE
+
+
+File: diffutils.info-t, Node: Making Patches, Next: Invoking cmp, Prev: Merging with patch, Up: Top
+
+11 Tips for Making and Using Patches
+************************************
+
+Use some common sense when making and using patches. For example, when
+sending bug fixes to a program's maintainer, send several small patches,
+one per independent subject, instead of one large, harder-to-digest
+patch that covers all the subjects.
+
+ Here are some other things you should keep in mind if you are going
+to distribute patches for updating a software package.
+
+* Menu:
+
+* Tips for Patch Producers:: Advice for making patches.
+* Tips for Patch Consumers:: Advice for using patches.
+* Avoiding Common Mistakes:: Avoiding common mistakes when using 'patch'.
+* Generating Smaller Patches:: How to generate smaller patches.
+
+
+File: diffutils.info-t, Node: Tips for Patch Producers, Next: Tips for Patch Consumers, Up: Making Patches
+
+11.1 Tips for Patch Producers
+=============================
+
+To create a patch that changes an older version of a package into a
+newer version, first make a copy of the older and newer versions in
+adjacent subdirectories. It is common to do that by unpacking 'tar'
+archives of the two versions.
+
+ To generate the patch, use the command 'diff -Naur OLD NEW' where OLD
+and NEW identify the old and new directories. The names OLD and NEW
+should not contain any slashes. The '-N' option lets the patch create
+and remove files; '-a' lets the patch update non-text files; '-u'
+generates useful time stamps and enough context; and '-r' lets the patch
+update subdirectories. Here is an example command, using Bourne shell
+syntax:
+
+ diff -Naur gcc-3.0.3 gcc-3.0.4
+
+ Tell your recipients how to apply the patches. This should include
+which working directory to use, and which 'patch' options to use; the
+option '-p1' is recommended. Test your procedure by pretending to be a
+recipient and applying your patches to a copy of the original files.
+
+ *Note Avoiding Common Mistakes::, for how to avoid common mistakes
+when generating a patch.
+
+
+File: diffutils.info-t, Node: Tips for Patch Consumers, Next: Avoiding Common Mistakes, Prev: Tips for Patch Producers, Up: Making Patches
+
+11.2 Tips for Patch Consumers
+=============================
+
+A patch producer should tell recipients how to apply the patches, so the
+first rule of thumb for a patch consumer is to follow the instructions
+supplied with the patch.
+
+ GNU 'diff' can analyze files with arbitrarily long lines and files
+that end in incomplete lines. However, older versions of 'patch' cannot
+patch such files. If you are having trouble applying such patches, try
+upgrading to a recent version of GNU 'patch'.
+
+
+File: diffutils.info-t, Node: Avoiding Common Mistakes, Next: Generating Smaller Patches, Prev: Tips for Patch Consumers, Up: Making Patches
+
+11.3 Avoiding Common Mistakes
+=============================
+
+When producing a patch for multiple files, apply 'diff' to directories
+whose names do not have slashes. This reduces confusion when the patch
+consumer specifies the '-pNUMBER' option, since this option can have
+surprising results when the old and new file names have different
+numbers of slashes. For example, do not send a patch with a header that
+looks like this:
+
+ diff -Naur v2.0.29/prog/README prog/README
+ --- v2.0.29/prog/README 2002-03-10 23:30:39.942229878 -0800
+ +++ prog/README 2002-03-17 20:49:32.442260588 -0800
+
+because the two file names have different numbers of slashes, and
+different versions of 'patch' interpret the file names differently. To
+avoid confusion, send output that looks like this instead:
+
+ diff -Naur v2.0.29/prog/README v2.0.30/prog/README
+ --- v2.0.29/prog/README 2002-03-10 23:30:39.942229878 -0800
+ +++ v2.0.30/prog/README 2002-03-17 20:49:32.442260588 -0800
+
+ Make sure you have specified the file names correctly, either in a
+context diff header or with an 'Index:' line. Take care to not send out
+reversed patches, since these make people wonder whether they have
+already applied the patch.
+
+ Avoid sending patches that compare backup file names like
+'README.orig' or 'README~', since this might confuse 'patch' into
+patching a backup file instead of the real file. Instead, send patches
+that compare the same base file names in different directories, e.g.
+'old/README' and 'new/README'.
+
+ To save people from partially applying a patch before other patches
+that should have gone before it, you can make the first patch in the
+patch file update a file with a name like 'patchlevel.h' or 'version.c',
+which contains a patch level or version number. If the input file
+contains the wrong version number, 'patch' will complain immediately.
+
+ An even clearer way to prevent this problem is to put a 'Prereq:'
+line before the patch. If the leading text in the patch file contains a
+line that starts with 'Prereq:', 'patch' takes the next word from that
+line (normally a version number) and checks whether the next input file
+contains that word, preceded and followed by either white space or a
+newline. If not, 'patch' prompts you for confirmation before
+proceeding. This makes it difficult to accidentally apply patches in
+the wrong order.
+
+
+File: diffutils.info-t, Node: Generating Smaller Patches, Prev: Avoiding Common Mistakes, Up: Making Patches
+
+11.4 Generating Smaller Patches
+===============================
+
+The simplest way to generate a patch is to use 'diff -Naur' (*note Tips
+for Patch Producers::), but you might be able to reduce the size of the
+patch by renaming or removing some files before making the patch. If
+the older version of the package contains any files that the newer
+version does not, or if any files have been renamed between the two
+versions, make a list of 'rm' and 'mv' commands for the user to execute
+in the old version directory before applying the patch. Then run those
+commands yourself in the scratch directory.
+
+ If there are any files that you don't need to include in the patch
+because they can easily be rebuilt from other files (for example, 'TAGS'
+and output from 'yacc' and 'makeinfo'), exclude them from the patch by
+giving 'diff' the '-x PATTERN' option (*note Comparing Directories::).
+If you want your patch to modify a derived file because your recipients
+lack tools to build it, make sure that the patch for the derived file
+follows any patches for files that it depends on, so that the
+recipients' time stamps will not confuse 'make'.
+
+ Now you can create the patch using 'diff -Naur'. Make sure to
+specify the scratch directory first and the newer directory second.
+
+ Add to the top of the patch a note telling the user any 'rm' and 'mv'
+commands to run before applying the patch. Then you can remove the
+scratch directory.
+
+ You can also shrink the patch size by using fewer lines of context,
+but bear in mind that 'patch' typically needs at least two lines for
+proper operation when patches do not exactly match the input files.
+
+
+File: diffutils.info-t, Node: Invoking cmp, Next: Invoking diff, Prev: Making Patches, Up: Top
+
+12 Invoking 'cmp'
+*****************
+
+The 'cmp' command compares two files, and if they differ, tells the
+first byte and line number where they differ or reports that one file is
+a prefix of the other. Bytes and lines are numbered starting with 1.
+The arguments of 'cmp' are as follows:
+
+ cmp OPTIONS... FROM-FILE [TO-FILE [FROM-SKIP [TO-SKIP]]]
+
+ The file name '-' is always the standard input. 'cmp' also uses the
+standard input if one file name is omitted. The FROM-SKIP and TO-SKIP
+operands specify how many bytes to ignore at the start of each file;
+they are equivalent to the '--ignore-initial=FROM-SKIP:TO-SKIP' option.
+
+ By default, 'cmp' outputs nothing if the two files have the same
+contents. If one file is a prefix of the other, 'cmp' prints to
+standard error a message of the following form:
+
+ cmp: EOF on SHORTER-FILE
+
+ Otherwise, 'cmp' prints to standard output a message of the following
+form:
+
+ FROM-FILE TO-FILE differ: char BYTE-NUMBER, line LINE-NUMBER
+
+ The message formats can differ outside the POSIX locale. Also, POSIX
+allows the EOF message to be followed by a blank and some additional
+information.
+
+ An exit status of 0 means no differences were found, 1 means some
+differences were found, and 2 means trouble.
+
+* Menu:
+
+* cmp Options:: Summary of options to 'cmp'.
+
+
+File: diffutils.info-t, Node: cmp Options, Up: Invoking cmp
+
+12.1 Options to 'cmp'
+=====================
+
+Below is a summary of all of the options that GNU 'cmp' accepts. Most
+options have two equivalent names, one of which is a single letter
+preceded by '-', and the other of which is a long name preceded by '--'.
+Multiple single letter options (unless they take an argument) can be
+combined into a single command line word: '-bl' is equivalent to '-b
+-l'.
+
+'-b'
+'--print-bytes'
+ Print the differing bytes. Display control bytes as a '^' followed
+ by a letter of the alphabet and precede bytes that have the high
+ bit set with 'M-' (which stands for "meta").
+
+'--help'
+ Output a summary of usage and then exit.
+
+'-i SKIP'
+'--ignore-initial=SKIP'
+ Ignore any differences in the first SKIP bytes of the input files.
+ Treat files with fewer than SKIP bytes as if they are empty. If
+ SKIP is of the form 'FROM-SKIP:TO-SKIP', skip the first FROM-SKIP
+ bytes of the first input file and the first TO-SKIP bytes of the
+ second.
+
+'-l'
+'--verbose'
+ Output the (decimal) byte numbers and (octal) values of all
+ differing bytes, instead of the default standard output. Each
+ output line contains a differing byte's number relative to the
+ start of the input, followed by the differing byte values. Byte
+ numbers start at 1. Also, output the EOF message if one file is
+ shorter than the other.
+
+'-n COUNT'
+'--bytes=COUNT'
+ Compare at most COUNT input bytes.
+
+'-s'
+'--quiet'
+'--silent'
+ Do not print anything; only return an exit status indicating
+ whether the files differ.
+
+'-v'
+'--version'
+ Output version information and then exit.
+
+ In the above table, operands that are byte counts are normally
+decimal, but may be preceded by '0' for octal and '0x' for hexadecimal.
+
+ A byte count can be followed by a suffix to specify a multiple of
+that count; in this case an omitted integer is understood to be 1. A
+bare size letter, or one followed by 'iB', specifies a multiple using
+powers of 1024. A size letter followed by 'B' specifies powers of 1000
+instead. For example, '-n 4M' and '-n 4MiB' are equivalent to '-n
+4194304', whereas '-n 4MB' is equivalent to '-n 4000000'. This notation
+is upward compatible with the SI prefixes
+(http://www.bipm.fr/enus/3_SI/si-prefixes.html) for decimal multiples
+and with the IEC 60027-2 prefixes for binary multiples
+(http://physics.nist.gov/cuu/Units/binary.html).
+
+ The following suffixes are defined. Large sizes like '1Y' may be
+rejected by your computer due to limitations of its arithmetic.
+
+'kB'
+ kilobyte: 10^3 = 1000.
+'k'
+'K'
+'KiB'
+ kibibyte: 2^10 = 1024. 'K' is special: the SI prefix is 'k' and
+ the IEC 60027-2 prefix is 'Ki', but tradition and POSIX use 'k' to
+ mean 'KiB'.
+'MB'
+ megabyte: 10^6 = 1,000,000.
+'M'
+'MiB'
+ mebibyte: 2^20 = 1,048,576.
+'GB'
+ gigabyte: 10^9 = 1,000,000,000.
+'G'
+'GiB'
+ gibibyte: 2^30 = 1,073,741,824.
+'TB'
+ terabyte: 10^12 = 1,000,000,000,000.
+'T'
+'TiB'
+ tebibyte: 2^40 = 1,099,511,627,776.
+'PB'
+ petabyte: 10^15 = 1,000,000,000,000,000.
+'P'
+'PiB'
+ pebibyte: 2^50 = 1,125,899,906,842,624.
+'EB'
+ exabyte: 10^18 = 1,000,000,000,000,000,000.
+'E'
+'EiB'
+ exbibyte: 2^60 = 1,152,921,504,606,846,976.
+'ZB'
+ zettabyte: 10^21 = 1,000,000,000,000,000,000,000
+'Z'
+'ZiB'
+ 2^70 = 1,180,591,620,717,411,303,424. ('Zi' is a GNU extension to
+ IEC 60027-2.)
+'YB'
+ yottabyte: 10^24 = 1,000,000,000,000,000,000,000,000.
+'Y'
+'YiB'
+ 2^80 = 1,208,925,819,614,629,174,706,176. ('Yi' is a GNU extension
+ to IEC 60027-2.)
+
+
+File: diffutils.info-t, Node: Invoking diff, Next: Invoking diff3, Prev: Invoking cmp, Up: Top
+
+13 Invoking 'diff'
+******************
+
+The format for running the 'diff' command is:
+
+ diff OPTIONS... FILES...
+
+ In the simplest case, two file names FROM-FILE and TO-FILE are given,
+and 'diff' compares the contents of FROM-FILE and TO-FILE. A file name
+of '-' stands for the standard input.
+
+ If one file is a directory and the other is not, 'diff' compares the
+file in the directory whose name is that of the non-directory. The
+non-directory file must not be '-'.
+
+ If two file names are given and both are directories, 'diff' compares
+corresponding files in both directories, in alphabetical order; this
+comparison is not recursive unless the '--recursive' ('-r') option is
+given. 'diff' never compares the actual contents of a directory as if
+it were a file. The file that is fully specified may not be standard
+input, because standard input is nameless and the notion of "file with
+the same name" does not apply.
+
+ If the '--from-file=FILE' option is given, the number of file names
+is arbitrary, and FILE is compared to each named file. Similarly, if
+the '--to-file=FILE' option is given, each named file is compared to
+FILE.
+
+ 'diff' options begin with '-', so normally file names may not begin
+with '-'. However, '--' as an argument by itself treats the remaining
+arguments as file names even if they begin with '-'.
+
+ An exit status of 0 means no differences were found, 1 means some
+differences were found, and 2 means trouble.
+
+* Menu:
+
+* diff Options:: Summary of options to 'diff'.
+
+
+File: diffutils.info-t, Node: diff Options, Up: Invoking diff
+
+13.1 Options to 'diff'
+======================
+
+Below is a summary of all of the options that GNU 'diff' accepts. Most
+options have two equivalent names, one of which is a single letter
+preceded by '-', and the other of which is a long name preceded by '--'.
+Multiple single letter options (unless they take an argument) can be
+combined into a single command line word: '-ac' is equivalent to '-a
+-c'. Long named options can be abbreviated to any unique prefix of
+their name. Brackets ([ and ]) indicate that an option takes an
+optional argument.
+
+'-a'
+'--text'
+ Treat all files as text and compare them line-by-line, even if they
+ do not seem to be text. *Note Binary::.
+
+'-b'
+'--ignore-space-change'
+ Ignore changes in amount of white space. *Note White Space::.
+
+'-B'
+'--ignore-blank-lines'
+ Ignore changes that just insert or delete blank lines. *Note Blank
+ Lines::.
+
+'--binary'
+ Read and write data in binary mode. *Note Binary::.
+
+'-c'
+ Use the context output format, showing three lines of context.
+ *Note Context Format::.
+
+'--color [=WHEN]'
+ Specify whether to use color for distinguishing different contexts,
+ like header, added or removed lines. WHEN may be omitted, or one
+ of:
+ * none Do not use color at all. This is the default when no
+ -color option is specified.
+ * auto Use color only if standard output is a terminal.
+ * always Always use color.
+ Specifying '--color' and no WHEN is equivalent to '--color=auto'.
+
+'-C LINES'
+'--context[=LINES]'
+ Use the context output format, showing LINES (an integer) lines of
+ context, or three if LINES is not given. *Note Context Format::.
+ For proper operation, 'patch' typically needs at least two lines of
+ context.
+
+ For compatibility 'diff' also supports an obsolete option syntax
+ '-LINES' that has effect when combined with '-c', '-p', or '-u'.
+ New scripts should use '-U LINES' ('-C LINES') instead.
+
+'--changed-group-format=FORMAT'
+ Use FORMAT to output a line group containing differing lines from
+ both files in if-then-else format. *Note Line Group Formats::.
+
+'-d'
+'--minimal'
+ Change the algorithm perhaps find a smaller set of changes. This
+ makes 'diff' slower (sometimes much slower). *Note diff
+ Performance::.
+
+'-D NAME'
+'--ifdef=NAME'
+ Make merged '#ifdef' format output, conditional on the preprocessor
+ macro NAME. *Note If-then-else::.
+
+'-e'
+'--ed'
+ Make output that is a valid 'ed' script. *Note ed Scripts::.
+
+'-E'
+'--ignore-tab-expansion'
+ Ignore changes due to tab expansion. *Note White Space::.
+
+'-f'
+'--forward-ed'
+ Make output that looks vaguely like an 'ed' script but has changes
+ in the order they appear in the file. *Note Forward ed::.
+
+'-F REGEXP'
+'--show-function-line=REGEXP'
+ In context and unified format, for each hunk of differences, show
+ some of the last preceding line that matches REGEXP. *Note
+ Specified Headings::.
+
+'--from-file=FILE'
+ Compare FILE to each operand; FILE may be a directory.
+
+'--help'
+ Output a summary of usage and then exit.
+
+'--horizon-lines=LINES'
+ Do not discard the last LINES lines of the common prefix and the
+ first LINES lines of the common suffix. *Note diff Performance::.
+
+'-i'
+'--ignore-case'
+ Ignore changes in case; consider upper- and lower-case letters
+ equivalent. *Note Case Folding::.
+
+'-I REGEXP'
+'--ignore-matching-lines=REGEXP'
+ Ignore changes that just insert or delete lines that match REGEXP.
+ *Note Specified Lines::.
+
+'--ignore-file-name-case'
+ Ignore case when comparing file names. For example, recursive
+ comparison of 'd' to 'e' might compare the contents of 'd/Init' and
+ 'e/inIt'. At the top level, 'diff d inIt' might compare the
+ contents of 'd/Init' and 'inIt'. *Note Comparing Directories::.
+
+'-l'
+'--paginate'
+ Pass the output through 'pr' to paginate it. *Note Pagination::.
+
+'-L LABEL'
+'--label=LABEL'
+ Use LABEL instead of the file name in the context format (*note
+ Context Format::) and unified format (*note Unified Format::)
+ headers. *Note RCS::.
+
+'--left-column'
+ Print only the left column of two common lines in side by side
+ format. *Note Side by Side Format::.
+
+'--line-format=FORMAT'
+ Use FORMAT to output all input lines in if-then-else format. *Note
+ Line Formats::.
+
+'-n'
+'--rcs'
+ Output RCS-format diffs; like '-f' except that each command
+ specifies the number of lines affected. *Note RCS::.
+
+'-N'
+'--new-file'
+ If one file is missing, treat it as present but empty. *Note
+ Comparing Directories::.
+
+'--new-group-format=FORMAT'
+ Use FORMAT to output a group of lines taken from just the second
+ file in if-then-else format. *Note Line Group Formats::.
+
+'--new-line-format=FORMAT'
+ Use FORMAT to output a line taken from just the second file in
+ if-then-else format. *Note Line Formats::.
+
+'--no-dereference'
+ Act on symbolic links themselves instead of what they point to.
+ Two symbolic links are deemed equal only when each points to
+ precisely the same name.
+
+'--old-group-format=FORMAT'
+ Use FORMAT to output a group of lines taken from just the first
+ file in if-then-else format. *Note Line Group Formats::.
+
+'--old-line-format=FORMAT'
+ Use FORMAT to output a line taken from just the first file in
+ if-then-else format. *Note Line Formats::.
+
+'-p'
+'--show-c-function'
+ Show which C function each change is in. *Note C Function
+ Headings::.
+
+'--palette=PALETTE'
+ Specify what color palette to use when colored output is enabled.
+ It defaults to 'rs=0:hd=1:ad=32:de=31:ln=36' for red deleted lines,
+ green added lines, cyan line numbers, bold header.
+
+ Supported capabilities are as follows.
+
+ 'ad=32'
+
+ SGR substring for added lines. The default is green
+ foreground.
+
+ 'de=31'
+
+ SGR substring for deleted lines. The default is red
+ foreground.
+
+ 'hd=1'
+
+ SGR substring for chunk header. The default is bold
+ foreground.
+
+ 'ln=36'
+
+ SGR substring for line numbers. The default is cyan
+ foreground.
+
+'-q'
+'--brief'
+ Report only whether the files differ, not the details of the
+ differences. *Note Brief::.
+
+'-r'
+'--recursive'
+ When comparing directories, recursively compare any subdirectories
+ found. *Note Comparing Directories::.
+
+'-s'
+'--report-identical-files'
+ Report when two files are the same. *Note Comparing Directories::.
+
+'-S FILE'
+'--starting-file=FILE'
+ When comparing directories, start with the file FILE. This is used
+ for resuming an aborted comparison. *Note Comparing Directories::.
+
+'--speed-large-files'
+ Use heuristics to speed handling of large files that have numerous
+ scattered small changes. *Note diff Performance::.
+
+'--strip-trailing-cr'
+ Strip any trailing carriage return at the end of an input line.
+ *Note Binary::.
+
+'--suppress-common-lines'
+ Do not print common lines in side by side format. *Note Side by
+ Side Format::.
+
+'-t'
+'--expand-tabs'
+ Expand tabs to spaces in the output, to preserve the alignment of
+ tabs in the input files. *Note Tabs::.
+
+'-T'
+'--initial-tab'
+ Output a tab rather than a space before the text of a line in
+ normal or context format. This causes the alignment of tabs in the
+ line to look normal. *Note Tabs::.
+
+'--tabsize=COLUMNS'
+ Assume that tab stops are set every COLUMNS (default 8) print
+ columns. *Note Tabs::.
+
+'--suppress-blank-empty'
+ Suppress any blanks before newlines when printing the
+ representation of an empty line, when outputting normal, context,
+ or unified format. *Note Trailing Blanks::.
+
+'--to-file=FILE'
+ Compare each operand to FILE; FILE may be a directory.
+
+'-u'
+ Use the unified output format, showing three lines of context.
+ *Note Unified Format::.
+
+'--unchanged-group-format=FORMAT'
+ Use FORMAT to output a group of common lines taken from both files
+ in if-then-else format. *Note Line Group Formats::.
+
+'--unchanged-line-format=FORMAT'
+ Use FORMAT to output a line common to both files in if-then-else
+ format. *Note Line Formats::.
+
+'--unidirectional-new-file'
+ If a first file is missing, treat it as present but empty. *Note
+ Comparing Directories::.
+
+'-U LINES'
+'--unified[=LINES]'
+ Use the unified output format, showing LINES (an integer) lines of
+ context, or three if LINES is not given. *Note Unified Format::.
+ For proper operation, 'patch' typically needs at least two lines of
+ context.
+
+ On older systems, 'diff' supports an obsolete option '-LINES' that
+ has effect when combined with '-u'. POSIX 1003.1-2001 (*note
+ Standards conformance::) does not allow this; use '-U LINES'
+ instead.
+
+'-v'
+'--version'
+ Output version information and then exit.
+
+'-w'
+'--ignore-all-space'
+ Ignore white space when comparing lines. *Note White Space::.
+
+'-W COLUMNS'
+'--width=COLUMNS'
+ Output at most COLUMNS (default 130) print columns per line in side
+ by side format. *Note Side by Side Format::.
+
+'-x PATTERN'
+'--exclude=PATTERN'
+ When comparing directories, ignore files and subdirectories whose
+ basenames match PATTERN. *Note Comparing Directories::.
+
+'-X FILE'
+'--exclude-from=FILE'
+ When comparing directories, ignore files and subdirectories whose
+ basenames match any pattern contained in FILE. *Note Comparing
+ Directories::.
+
+'-y'
+'--side-by-side'
+ Use the side by side output format. *Note Side by Side Format::.
+
+'-Z'
+'--ignore-trailing-space'
+ Ignore white space at line end. *Note White Space::.
+
+
+File: diffutils.info-t, Node: Invoking diff3, Next: Invoking patch, Prev: Invoking diff, Up: Top
+
+14 Invoking 'diff3'
+*******************
+
+The 'diff3' command compares three files and outputs descriptions of
+their differences. Its arguments are as follows:
+
+ diff3 OPTIONS... MINE OLDER YOURS
+
+ The files to compare are MINE, OLDER, and YOURS. At most one of
+these three file names may be '-', which tells 'diff3' to read the
+standard input for that file.
+
+ An exit status of 0 means 'diff3' was successful, 1 means some
+conflicts were found, and 2 means trouble.
+
+* Menu:
+
+* diff3 Options:: Summary of options to 'diff3'.
+
+
+File: diffutils.info-t, Node: diff3 Options, Up: Invoking diff3
+
+14.1 Options to 'diff3'
+=======================
+
+Below is a summary of all of the options that GNU 'diff3' accepts.
+Multiple single letter options (unless they take an argument) can be
+combined into a single command line argument.
+
+'-a'
+'--text'
+ Treat all files as text and compare them line-by-line, even if they
+ do not appear to be text. *Note Binary::.
+
+'-A'
+'--show-all'
+ Incorporate all unmerged changes from OLDER to YOURS into MINE,
+ surrounding conflicts with bracket lines. *Note Marking
+ Conflicts::.
+
+'--diff-program=PROGRAM'
+ Use the compatible comparison program PROGRAM to compare files
+ instead of 'diff'.
+
+'-e'
+'--ed'
+ Generate an 'ed' script that incorporates all the changes from
+ OLDER to YOURS into MINE. *Note Which Changes::.
+
+'-E'
+'--show-overlap'
+ Like '-e', except bracket lines from overlapping changes' first and
+ third files. *Note Marking Conflicts::. With '-E', an overlapping
+ change looks like this:
+
+ <<<<<<< MINE
+ lines from MINE
+ =======
+ lines from YOURS
+ >>>>>>> YOURS
+
+'--help'
+ Output a summary of usage and then exit.
+
+'-i'
+ Generate 'w' and 'q' commands at the end of the 'ed' script for
+ System V compatibility. This option must be combined with one of
+ the '-AeExX3' options, and may not be combined with '-m'. *Note
+ Saving the Changed File::.
+
+'--label=LABEL'
+ Use the label LABEL for the brackets output by the '-A', '-E' and
+ '-X' options. This option may be given up to three times, one for
+ each input file. The default labels are the names of the input
+ files. Thus 'diff3 --label X --label Y --label Z -m A B C' acts
+ like 'diff3 -m A B C', except that the output looks like it came
+ from files named 'X', 'Y' and 'Z' rather than from files named 'A',
+ 'B' and 'C'. *Note Marking Conflicts::.
+
+'-m'
+'--merge'
+ Apply the edit script to the first file and send the result to
+ standard output. Unlike piping the output from 'diff3' to 'ed',
+ this works even for binary files and incomplete lines. '-A' is
+ assumed if no edit script option is specified. *Note Bypassing
+ ed::.
+
+'--strip-trailing-cr'
+ Strip any trailing carriage return at the end of an input line.
+ *Note Binary::.
+
+'-T'
+'--initial-tab'
+ Output a tab rather than two spaces before the text of a line in
+ normal format. This causes the alignment of tabs in the line to
+ look normal. *Note Tabs::.
+
+'-v'
+'--version'
+ Output version information and then exit.
+
+'-x'
+'--overlap-only'
+ Like '-e', except output only the overlapping changes. *Note Which
+ Changes::.
+
+'-X'
+ Like '-E', except output only the overlapping changes. In other
+ words, like '-x', except bracket changes as in '-E'. *Note Marking
+ Conflicts::.
+
+'-3'
+'--easy-only'
+ Like '-e', except output only the nonoverlapping changes. *Note
+ Which Changes::.
+
+
+File: diffutils.info-t, Node: Invoking patch, Next: Invoking sdiff, Prev: Invoking diff3, Up: Top
+
+15 Invoking 'patch'
+*******************
+
+Normally 'patch' is invoked like this:
+
+ patch <PATCHFILE
+
+ The full format for invoking 'patch' is:
+
+ patch OPTIONS... [ORIGFILE [PATCHFILE]]
+
+ You can also specify where to read the patch from with the '-i
+PATCHFILE' or '--input=PATCHFILE' option. If you do not specify
+PATCHFILE, or if PATCHFILE is '-', 'patch' reads the patch (that is, the
+'diff' output) from the standard input.
+
+ If you do not specify an input file on the command line, 'patch'
+tries to intuit from the "leading text" (any text in the patch that
+comes before the 'diff' output) which file to edit. *Note Multiple
+Patches::.
+
+ By default, 'patch' replaces the original input file with the patched
+version, possibly after renaming the original file into a backup file
+(*note Backup Names::, for a description of how 'patch' names backup
+files). You can also specify where to put the output with the '-o FILE'
+or '--output=FILE' option; however, do not use this option if FILE is
+one of the input files.
+
+* Menu:
+
+* patch Options:: Summary table of options to 'patch'.
+
+
+File: diffutils.info-t, Node: patch Options, Up: Invoking patch
+
+15.1 Options to 'patch'
+=======================
+
+Here is a summary of all of the options that GNU 'patch' accepts. *Note
+patch and Tradition::, for which of these options are safe to use in
+older versions of 'patch'.
+
+ Multiple single-letter options that do not take an argument can be
+combined into a single command line argument with only one dash.
+
+'-b'
+'--backup'
+ Back up the original contents of each file, even if backups would
+ normally not be made. *Note Backups::.
+
+'-B PREFIX'
+'--prefix=PREFIX'
+ Prepend PREFIX to backup file names. *Note Backup Names::.
+
+'--backup-if-mismatch'
+ Back up the original contents of each file if the patch does not
+ exactly match the file. This is the default behavior when not
+ conforming to POSIX. *Note Backups::.
+
+'--binary'
+ Read and write all files in binary mode, except for standard output
+ and '/dev/tty'. This option has no effect on POSIX-conforming
+ systems like GNU/Linux. On systems where this option makes a
+ difference, the patch should be generated by 'diff -a --binary'.
+ *Note Binary::.
+
+'-c'
+'--context'
+ Interpret the patch file as a context diff. *Note patch Input::.
+
+'-d DIRECTORY'
+'--directory=DIRECTORY'
+ Make directory DIRECTORY the current directory for interpreting
+ both file names in the patch file, and file names given as
+ arguments to other options. *Note patch Directories::.
+
+'-D NAME'
+'--ifdef=NAME'
+ Make merged if-then-else output using NAME. *Note If-then-else::.
+
+'--dry-run'
+ Print the results of applying the patches without actually changing
+ any files. *Note Dry Runs::.
+
+'-e'
+'--ed'
+ Interpret the patch file as an 'ed' script. *Note patch Input::.
+
+'-E'
+'--remove-empty-files'
+ Remove output files that are empty after the patches have been
+ applied. *Note Creating and Removing::.
+
+'-f'
+'--force'
+ Assume that the user knows exactly what he or she is doing, and do
+ not ask any questions. *Note patch Messages::.
+
+'-F LINES'
+'--fuzz=LINES'
+ Set the maximum fuzz factor to LINES. *Note Inexact::.
+
+'-g NUM'
+'--get=NUM'
+ If NUM is positive, get input files from a revision control system
+ as necessary; if zero, do not get the files; if negative, ask the
+ user whether to get the files. *Note Revision Control::.
+
+'--help'
+ Output a summary of usage and then exit.
+
+'-i PATCHFILE'
+'--input=PATCHFILE'
+ Read the patch from PATCHFILE rather than from standard input.
+ *Note patch Options::.
+
+'-l'
+'--ignore-white-space'
+ Let any sequence of blanks (spaces or tabs) in the patch file match
+ any sequence of blanks in the input file. *Note Changed White
+ Space::.
+
+'-n'
+'--normal'
+ Interpret the patch file as a normal diff. *Note patch Input::.
+
+'-N'
+'--forward'
+ Ignore patches that 'patch' thinks are reversed or already applied.
+ See also '-R'. *Note Reversed Patches::.
+
+'--no-backup-if-mismatch'
+ Do not back up the original contents of files. This is the default
+ behavior when conforming to POSIX. *Note Backups::.
+
+'-o FILE'
+'--output=FILE'
+ Use FILE as the output file name. *Note patch Options::.
+
+'-pNUMBER'
+'--strip=NUMBER'
+ Set the file name strip count to NUMBER. *Note patch
+ Directories::.
+
+'--posix'
+ Conform to POSIX, as if the 'POSIXLY_CORRECT' environment variable
+ had been set. *Note patch and POSIX::.
+
+'--quoting-style=WORD'
+ Use style WORD to quote names in diagnostics, as if the
+ 'QUOTING_STYLE' environment variable had been set to WORD. *Note
+ patch Quoting Style::.
+
+'-r REJECT-FILE'
+'--reject-file=REJECT-FILE'
+ Use REJECT-FILE as the reject file name. *Note Reject Names::.
+
+'-R'
+'--reverse'
+ Assume that this patch was created with the old and new files
+ swapped. *Note Reversed Patches::.
+
+'-s'
+'--quiet'
+'--silent'
+ Work silently unless an error occurs. *Note patch Messages::.
+
+'-t'
+'--batch'
+ Do not ask any questions. *Note patch Messages::.
+
+'-T'
+'--set-time'
+ Set the modification and access times of patched files from time
+ stamps given in context diff headers, assuming that the context
+ diff headers use local time. *Note Patching Time Stamps::.
+
+'-u'
+'--unified'
+ Interpret the patch file as a unified diff. *Note patch Input::.
+
+'-v'
+'--version'
+ Output version information and then exit.
+
+'-V BACKUP-STYLE'
+'--version=control=BACKUP-STYLE'
+ Select the naming convention for backup file names. *Note Backup
+ Names::.
+
+'--verbose'
+ Print more diagnostics than usual. *Note patch Messages::.
+
+'-x NUMBER'
+'--debug=NUMBER'
+ Set internal debugging flags. Of interest only to 'patch'
+ patchers.
+
+'-Y PREFIX'
+'--basename-prefix=PREFIX'
+ Prepend PREFIX to base names of backup files. *Note Backup
+ Names::.
+
+'-z SUFFIX'
+'--suffix=SUFFIX'
+ Use SUFFIX as the backup extension instead of '.orig' or '~'.
+ *Note Backup Names::.
+
+'-Z'
+'--set-utc'
+ Set the modification and access times of patched files from time
+ stamps given in context diff headers, assuming that the context
+ diff headers use UTC. *Note Patching Time Stamps::.
+
+
+File: diffutils.info-t, Node: Invoking sdiff, Next: Standards conformance, Prev: Invoking patch, Up: Top
+
+16 Invoking 'sdiff'
+*******************
+
+The 'sdiff' command merges two files and interactively outputs the
+results. Its arguments are as follows:
+
+ sdiff -o OUTFILE OPTIONS... FROM-FILE TO-FILE
+
+ This merges FROM-FILE with TO-FILE, with output to OUTFILE. If
+FROM-FILE is a directory and TO-FILE is not, 'sdiff' compares the file
+in FROM-FILE whose file name is that of TO-FILE, and vice versa.
+FROM-FILE and TO-FILE may not both be directories.
+
+ 'sdiff' options begin with '-', so normally FROM-FILE and TO-FILE may
+not begin with '-'. However, '--' as an argument by itself treats the
+remaining arguments as file names even if they begin with '-'. You may
+not use '-' as an input file.
+
+ 'sdiff' without '--output' ('-o') produces a side-by-side difference.
+This usage is obsolete; use the '--side-by-side' ('-y') option of 'diff'
+instead.
+
+ An exit status of 0 means no differences were found, 1 means some
+differences were found, and 2 means trouble.
+
+* Menu:
+
+* sdiff Options:: Summary of options to 'diff'.
+
+
+File: diffutils.info-t, Node: sdiff Options, Up: Invoking sdiff
+
+16.1 Options to 'sdiff'
+=======================
+
+Below is a summary of all of the options that GNU 'sdiff' accepts. Each
+option has two equivalent names, one of which is a single letter
+preceded by '-', and the other of which is a long name preceded by '--'.
+Multiple single letter options (unless they take an argument) can be
+combined into a single command line argument. Long named options can be
+abbreviated to any unique prefix of their name.
+
+'-a'
+'--text'
+ Treat all files as text and compare them line-by-line, even if they
+ do not appear to be text. *Note Binary::.
+
+'-b'
+'--ignore-space-change'
+ Ignore changes in amount of white space. *Note White Space::.
+
+'-B'
+'--ignore-blank-lines'
+ Ignore changes that just insert or delete blank lines. *Note Blank
+ Lines::.
+
+'-d'
+'--minimal'
+ Change the algorithm to perhaps find a smaller set of changes.
+ This makes 'sdiff' slower (sometimes much slower). *Note diff
+ Performance::.
+
+'--diff-program=PROGRAM'
+ Use the compatible comparison program PROGRAM to compare files
+ instead of 'diff'.
+
+'-E'
+'--ignore-tab-expansion'
+ Ignore changes due to tab expansion. *Note White Space::.
+
+'--help'
+ Output a summary of usage and then exit.
+
+'-i'
+'--ignore-case'
+ Ignore changes in case; consider upper- and lower-case to be the
+ same. *Note Case Folding::.
+
+'-I REGEXP'
+'--ignore-matching-lines=REGEXP'
+ Ignore changes that just insert or delete lines that match REGEXP.
+ *Note Specified Lines::.
+
+'-l'
+'--left-column'
+ Print only the left column of two common lines. *Note Side by Side
+ Format::.
+
+'-o FILE'
+'--output=FILE'
+ Put merged output into FILE. This option is required for merging.
+
+'-s'
+'--suppress-common-lines'
+ Do not print common lines. *Note Side by Side Format::.
+
+'--speed-large-files'
+ Use heuristics to speed handling of large files that have numerous
+ scattered small changes. *Note diff Performance::.
+
+'--strip-trailing-cr'
+ Strip any trailing carriage return at the end of an input line.
+ *Note Binary::.
+
+'-t'
+'--expand-tabs'
+ Expand tabs to spaces in the output, to preserve the alignment of
+ tabs in the input files. *Note Tabs::.
+
+'--tabsize=COLUMNS'
+ Assume that tab stops are set every COLUMNS (default 8) print
+ columns. *Note Tabs::.
+
+'-v'
+'--version'
+ Output version information and then exit.
+
+'-w COLUMNS'
+'--width=COLUMNS'
+ Output at most COLUMNS (default 130) print columns per line. *Note
+ Side by Side Format::. Note that for historical reasons, this
+ option is '-W' in 'diff', '-w' in 'sdiff'.
+
+'-W'
+'--ignore-all-space'
+ Ignore white space when comparing lines. *Note White Space::.
+ Note that for historical reasons, this option is '-w' in 'diff',
+ '-W' in 'sdiff'.
+
+'-Z'
+'--ignore-trailing-space'
+ Ignore white space at line end. *Note White Space::.
+
+
+File: diffutils.info-t, Node: Standards conformance, Next: Projects, Prev: Invoking sdiff, Up: Top
+
+17 Standards conformance
+************************
+
+In a few cases, the GNU utilities' default behavior is incompatible with
+the POSIX standard. To suppress these incompatibilities, define the
+'POSIXLY_CORRECT' environment variable. Unless you are checking for
+POSIX conformance, you probably do not need to define 'POSIXLY_CORRECT'.
+
+ Normally options and operands can appear in any order, and programs
+act as if all the options appear before any operands. For example,
+'diff lao tzu -C 2' acts like 'diff -C 2 lao tzu', since '2' is an
+option-argument of '-C'. However, if the 'POSIXLY_CORRECT' environment
+variable is set, options must appear before operands, unless otherwise
+specified for a particular command.
+
+ Newer versions of POSIX are occasionally incompatible with older
+versions. For example, older versions of POSIX allowed the command
+'diff -c -10' to have the same meaning as 'diff -C 10', but POSIX
+1003.1-2001 'diff' no longer allows digit-string options like '-10'.
+
+ The GNU utilities normally conform to the version of POSIX that is
+standard for your system. To cause them to conform to a different
+version of POSIX, define the '_POSIX2_VERSION' environment variable to a
+value of the form YYYYMM specifying the year and month the standard was
+adopted. Two values are currently supported for '_POSIX2_VERSION':
+'199209' stands for POSIX 1003.2-1992, and '200112' stands for POSIX
+1003.1-2001. For example, if you are running older software that
+assumes an older version of POSIX and uses 'diff -c -10', you can work
+around the compatibility problems by setting '_POSIX2_VERSION=199209' in
+your environment.
+
+
+File: diffutils.info-t, Node: Projects, Next: Copying This Manual, Prev: Standards conformance, Up: Top
+
+18 Future Projects
+******************
+
+Here are some ideas for improving GNU 'diff' and 'patch'. The GNU
+project has identified some improvements as potential programming
+projects for volunteers. You can also help by reporting any bugs that
+you find.
+
+ If you are a programmer and would like to contribute something to the
+GNU project, please consider volunteering for one of these projects. If
+you are seriously contemplating work, please write to <gvc@gnu.org> to
+coordinate with other volunteers.
+
+* Menu:
+
+* Shortcomings:: Suggested projects for improvements.
+* Bugs:: Reporting bugs.
+
+
+File: diffutils.info-t, Node: Shortcomings, Next: Bugs, Up: Projects
+
+18.1 Suggested Projects for Improving GNU 'diff' and 'patch'
+============================================================
+
+One should be able to use GNU 'diff' to generate a patch from any pair
+of directory trees, and given the patch and a copy of one such tree, use
+'patch' to generate a faithful copy of the other. Unfortunately, some
+changes to directory trees cannot be expressed using current patch
+formats; also, 'patch' does not handle some of the existing formats.
+These shortcomings motivate the following suggested projects.
+
+* Menu:
+
+* Internationalization:: Handling multibyte and varying-width characters.
+* Changing Structure:: Handling changes to the directory structure.
+* Special Files:: Handling symbolic links, device special files, etc.
+* Unusual File Names:: Handling file names that contain unusual characters.
+* Time Stamp Order:: Outputting diffs in time stamp order.
+* Ignoring Changes:: Ignoring certain changes while showing others.
+* Speedups:: Improving performance.
+
+
+File: diffutils.info-t, Node: Internationalization, Next: Changing Structure, Up: Shortcomings
+
+18.1.1 Handling Multibyte and Varying-Width Characters
+------------------------------------------------------
+
+'diff', 'diff3' and 'sdiff' treat each line of input as a string of
+unibyte characters. This can mishandle multibyte characters in some
+cases. For example, when asked to ignore spaces, 'diff' does not
+properly ignore a multibyte space character.
+
+ Also, 'diff' currently assumes that each byte is one column wide, and
+this assumption is incorrect in some locales, e.g., locales that use
+UTF-8 encoding. This causes problems with the '-y' or '--side-by-side'
+option of 'diff'.
+
+ These problems need to be fixed without unduly affecting the
+performance of the utilities in unibyte environments.
+
+ The IBM GNU/Linux Technology Center Internationalization Team has
+proposed patches to support internationalized 'diff'
+(http://oss.software.ibm.com/developer/opensource/linux/patches/i18n/diffutils-2.7.2-i18n-0.1.patch.gz).
+Unfortunately, these patches are incomplete and are to an older version
+of 'diff', so more work needs to be done in this area.
+
+
+File: diffutils.info-t, Node: Changing Structure, Next: Special Files, Prev: Internationalization, Up: Shortcomings
+
+18.1.2 Handling Changes to the Directory Structure
+--------------------------------------------------
+
+'diff' and 'patch' do not handle some changes to directory structure.
+For example, suppose one directory tree contains a directory named 'D'
+with some subsidiary files, and another contains a file with the same
+name 'D'. 'diff -r' does not output enough information for 'patch' to
+transform the directory subtree into the file.
+
+ There should be a way to specify that a file has been removed without
+having to include its entire contents in the patch file. There should
+also be a way to tell 'patch' that a file was renamed, even if there is
+no way for 'diff' to generate such information. There should be a way
+to tell 'patch' that a file's time stamp has changed, even if its
+contents have not changed.
+
+ These problems can be fixed by extending the 'diff' output format to
+represent changes in directory structure, and extending 'patch' to
+understand these extensions.
+
+
+File: diffutils.info-t, Node: Special Files, Next: Unusual File Names, Prev: Changing Structure, Up: Shortcomings
+
+18.1.3 Files that are Neither Directories Nor Regular Files
+-----------------------------------------------------------
+
+Some files are neither directories nor regular files: they are unusual
+files like symbolic links, device special files, named pipes, and
+sockets. Currently, 'diff' treats symbolic links as if they were the
+pointed-to files, except that a recursive 'diff' reports an error if it
+detects infinite loops of symbolic links (e.g., symbolic links to '..').
+'diff' treats other special files like regular files if they are
+specified at the top level, but simply reports their presence when
+comparing directories. This means that 'patch' cannot represent changes
+to such files. For example, if you change which file a symbolic link
+points to, 'diff' outputs the difference between the two files, instead
+of the change to the symbolic link.
+
+ 'diff' should optionally report changes to special files specially,
+and 'patch' should be extended to understand these extensions.
+
+
+File: diffutils.info-t, Node: Unusual File Names, Next: Time Stamp Order, Prev: Special Files, Up: Shortcomings
+
+18.1.4 File Names that Contain Unusual Characters
+-------------------------------------------------
+
+When a file name contains an unusual character like a newline or white
+space, 'diff -r' generates a patch that 'patch' cannot parse. The
+problem is with format of 'diff' output, not just with 'patch', because
+with odd enough file names one can cause 'diff' to generate a patch that
+is syntactically correct but patches the wrong files. The format of
+'diff' output should be extended to handle all possible file names.
+
+
+File: diffutils.info-t, Node: Time Stamp Order, Next: Ignoring Changes, Prev: Unusual File Names, Up: Shortcomings
+
+18.1.5 Outputting Diffs in Time Stamp Order
+-------------------------------------------
+
+Applying 'patch' to a multiple-file diff can result in files whose time
+stamps are out of order. GNU 'patch' has options to restore the time
+stamps of the updated files (*note Patching Time Stamps::), but
+sometimes it is useful to generate a patch that works even if the
+recipient does not have GNU patch, or does not use these options. One
+way to do this would be to implement a 'diff' option to output diffs in
+time stamp order.
+
+
+File: diffutils.info-t, Node: Ignoring Changes, Next: Speedups, Prev: Time Stamp Order, Up: Shortcomings
+
+18.1.6 Ignoring Certain Changes
+-------------------------------
+
+It would be nice to have a feature for specifying two strings, one in
+FROM-FILE and one in TO-FILE, which should be considered to match.
+Thus, if the two strings are 'foo' and 'bar', then if two lines differ
+only in that 'foo' in file 1 corresponds to 'bar' in file 2, the lines
+are treated as identical.
+
+ It is not clear how general this feature can or should be, or what
+syntax should be used for it.
+
+ A partial substitute is to filter one or both files before comparing,
+e.g.:
+
+ sed 's/foo/bar/g' file1 | diff - file2
+
+ However, this outputs the filtered text, not the original.
+
+
+File: diffutils.info-t, Node: Speedups, Prev: Ignoring Changes, Up: Shortcomings
+
+18.1.7 Improving Performance
+----------------------------
+
+When comparing two large directory structures, one of which was
+originally copied from the other with time stamps preserved (e.g., with
+'cp -pR'), it would greatly improve performance if an option told 'diff'
+to assume that two files with the same size and time stamps have the
+same content. *Note diff Performance::.
+
+
+File: diffutils.info-t, Node: Bugs, Prev: Shortcomings, Up: Projects
+
+18.2 Reporting Bugs
+===================
+
+If you think you have found a bug in GNU 'cmp', 'diff', 'diff3', or
+'sdiff', please report it by electronic mail to the GNU utilities bug
+report mailing list (http://mail.gnu.org/mailman/listinfo/bug-diffutils)
+<bug-diffutils@gnu.org>. Please send bug reports for GNU 'patch' to
+<bug-patch@gnu.org>. Send as precise a description of the problem as
+you can, including the output of the '--version' option and sample input
+files that produce the bug, if applicable. If you have a nontrivial fix
+for the bug, please send it as well. If you have a patch, please send
+it too. It may simplify the maintainer's job if the patch is relative
+to a recent test release, which you can find in the directory
+<ftp://alpha.gnu.org/gnu/diffutils/>.
+
+
+File: diffutils.info-t, Node: Copying This Manual, Next: Translations, Prev: Projects, Up: Top
+
+Appendix A Copying This Manual
+******************************
+
+ Version 1.3, 3 November 2008
+
+ Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
+ <http://fsf.org/>
+
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+ 0. PREAMBLE
+
+ The purpose of this License is to make a manual, textbook, or other
+ functional and useful document "free" in the sense of freedom: to
+ assure everyone the effective freedom to copy and redistribute it,
+ with or without modifying it, either commercially or
+ noncommercially. Secondarily, this License preserves for the
+ author and publisher a way to get credit for their work, while not
+ being considered responsible for modifications made by others.
+
+ This License is a kind of "copyleft", which means that derivative
+ works of the document must themselves be free in the same sense.
+ It complements the GNU General Public License, which is a copyleft
+ license designed for free software.
+
+ We have designed this License in order to use it for manuals for
+ free software, because free software needs free documentation: a
+ free program should come with manuals providing the same freedoms
+ that the software does. But this License is not limited to
+ software manuals; it can be used for any textual work, regardless
+ of subject matter or whether it is published as a printed book. We
+ recommend this License principally for works whose purpose is
+ instruction or reference.
+
+ 1. APPLICABILITY AND DEFINITIONS
+
+ This License applies to any manual or other work, in any medium,
+ that contains a notice placed by the copyright holder saying it can
+ be distributed under the terms of this License. Such a notice
+ grants a world-wide, royalty-free license, unlimited in duration,
+ to use that work under the conditions stated herein. The
+ "Document", below, refers to any such manual or work. Any member
+ of the public is a licensee, and is addressed as "you". You accept
+ the license if you copy, modify or distribute the work in a way
+ requiring permission under copyright law.
+
+ A "Modified Version" of the Document means any work containing the
+ Document or a portion of it, either copied verbatim, or with
+ modifications and/or translated into another language.
+
+ A "Secondary Section" is a named appendix or a front-matter section
+ of the Document that deals exclusively with the relationship of the
+ publishers or authors of the Document to the Document's overall
+ subject (or to related matters) and contains nothing that could
+ fall directly within that overall subject. (Thus, if the Document
+ is in part a textbook of mathematics, a Secondary Section may not
+ explain any mathematics.) The relationship could be a matter of
+ historical connection with the subject or with related matters, or
+ of legal, commercial, philosophical, ethical or political position
+ regarding them.
+
+ The "Invariant Sections" are certain Secondary Sections whose
+ titles are designated, as being those of Invariant Sections, in the
+ notice that says that the Document is released under this License.
+ If a section does not fit the above definition of Secondary then it
+ is not allowed to be designated as Invariant. The Document may
+ contain zero Invariant Sections. If the Document does not identify
+ any Invariant Sections then there are none.
+
+ The "Cover Texts" are certain short passages of text that are
+ listed, as Front-Cover Texts or Back-Cover Texts, in the notice
+ that says that the Document is released under this License. A
+ Front-Cover Text may be at most 5 words, and a Back-Cover Text may
+ be at most 25 words.
+
+ A "Transparent" copy of the Document means a machine-readable copy,
+ represented in a format whose specification is available to the
+ general public, that is suitable for revising the document
+ straightforwardly with generic text editors or (for images composed
+ of pixels) generic paint programs or (for drawings) some widely
+ available drawing editor, and that is suitable for input to text
+ formatters or for automatic translation to a variety of formats
+ suitable for input to text formatters. A copy made in an otherwise
+ Transparent file format whose markup, or absence of markup, has
+ been arranged to thwart or discourage subsequent modification by
+ readers is not Transparent. An image format is not Transparent if
+ used for any substantial amount of text. A copy that is not
+ "Transparent" is called "Opaque".
+
+ Examples of suitable formats for Transparent copies include plain
+ ASCII without markup, Texinfo input format, LaTeX input format,
+ SGML or XML using a publicly available DTD, and standard-conforming
+ simple HTML, PostScript or PDF designed for human modification.
+ Examples of transparent image formats include PNG, XCF and JPG.
+ Opaque formats include proprietary formats that can be read and
+ edited only by proprietary word processors, SGML or XML for which
+ the DTD and/or processing tools are not generally available, and
+ the machine-generated HTML, PostScript or PDF produced by some word
+ processors for output purposes only.
+
+ The "Title Page" means, for a printed book, the title page itself,
+ plus such following pages as are needed to hold, legibly, the
+ material this License requires to appear in the title page. For
+ works in formats which do not have any title page as such, "Title
+ Page" means the text near the most prominent appearance of the
+ work's title, preceding the beginning of the body of the text.
+
+ The "publisher" means any person or entity that distributes copies
+ of the Document to the public.
+
+ A section "Entitled XYZ" means a named subunit of the Document
+ whose title either is precisely XYZ or contains XYZ in parentheses
+ following text that translates XYZ in another language. (Here XYZ
+ stands for a specific section name mentioned below, such as
+ "Acknowledgements", "Dedications", "Endorsements", or "History".)
+ To "Preserve the Title" of such a section when you modify the
+ Document means that it remains a section "Entitled XYZ" according
+ to this definition.
+
+ The Document may include Warranty Disclaimers next to the notice
+ which states that this License applies to the Document. These
+ Warranty Disclaimers are considered to be included by reference in
+ this License, but only as regards disclaiming warranties: any other
+ implication that these Warranty Disclaimers may have is void and
+ has no effect on the meaning of this License.
+
+ 2. VERBATIM COPYING
+
+ You may copy and distribute the Document in any medium, either
+ commercially or noncommercially, provided that this License, the
+ copyright notices, and the license notice saying this License
+ applies to the Document are reproduced in all copies, and that you
+ add no other conditions whatsoever to those of this License. You
+ may not use technical measures to obstruct or control the reading
+ or further copying of the copies you make or distribute. However,
+ you may accept compensation in exchange for copies. If you
+ distribute a large enough number of copies you must also follow the
+ conditions in section 3.
+
+ You may also lend copies, under the same conditions stated above,
+ and you may publicly display copies.
+
+ 3. COPYING IN QUANTITY
+
+ If you publish printed copies (or copies in media that commonly
+ have printed covers) of the Document, numbering more than 100, and
+ the Document's license notice requires Cover Texts, you must
+ enclose the copies in covers that carry, clearly and legibly, all
+ these Cover Texts: Front-Cover Texts on the front cover, and
+ Back-Cover Texts on the back cover. Both covers must also clearly
+ and legibly identify you as the publisher of these copies. The
+ front cover must present the full title with all words of the title
+ equally prominent and visible. You may add other material on the
+ covers in addition. Copying with changes limited to the covers, as
+ long as they preserve the title of the Document and satisfy these
+ conditions, can be treated as verbatim copying in other respects.
+
+ If the required texts for either cover are too voluminous to fit
+ legibly, you should put the first ones listed (as many as fit
+ reasonably) on the actual cover, and continue the rest onto
+ adjacent pages.
+
+ If you publish or distribute Opaque copies of the Document
+ numbering more than 100, you must either include a machine-readable
+ Transparent copy along with each Opaque copy, or state in or with
+ each Opaque copy a computer-network location from which the general
+ network-using public has access to download using public-standard
+ network protocols a complete Transparent copy of the Document, free
+ of added material. If you use the latter option, you must take
+ reasonably prudent steps, when you begin distribution of Opaque
+ copies in quantity, to ensure that this Transparent copy will
+ remain thus accessible at the stated location until at least one
+ year after the last time you distribute an Opaque copy (directly or
+ through your agents or retailers) of that edition to the public.
+
+ It is requested, but not required, that you contact the authors of
+ the Document well before redistributing any large number of copies,
+ to give them a chance to provide you with an updated version of the
+ Document.
+
+ 4. MODIFICATIONS
+
+ You may copy and distribute a Modified Version of the Document
+ under the conditions of sections 2 and 3 above, provided that you
+ release the Modified Version under precisely this License, with the
+ Modified Version filling the role of the Document, thus licensing
+ distribution and modification of the Modified Version to whoever
+ possesses a copy of it. In addition, you must do these things in
+ the Modified Version:
+
+ A. Use in the Title Page (and on the covers, if any) a title
+ distinct from that of the Document, and from those of previous
+ versions (which should, if there were any, be listed in the
+ History section of the Document). You may use the same title
+ as a previous version if the original publisher of that
+ version gives permission.
+
+ B. List on the Title Page, as authors, one or more persons or
+ entities responsible for authorship of the modifications in
+ the Modified Version, together with at least five of the
+ principal authors of the Document (all of its principal
+ authors, if it has fewer than five), unless they release you
+ from this requirement.
+
+ C. State on the Title page the name of the publisher of the
+ Modified Version, as the publisher.
+
+ D. Preserve all the copyright notices of the Document.
+
+ E. Add an appropriate copyright notice for your modifications
+ adjacent to the other copyright notices.
+
+ F. Include, immediately after the copyright notices, a license
+ notice giving the public permission to use the Modified
+ Version under the terms of this License, in the form shown in
+ the Addendum below.
+
+ G. Preserve in that license notice the full lists of Invariant
+ Sections and required Cover Texts given in the Document's
+ license notice.
+
+ H. Include an unaltered copy of this License.
+
+ I. Preserve the section Entitled "History", Preserve its Title,
+ and add to it an item stating at least the title, year, new
+ authors, and publisher of the Modified Version as given on the
+ Title Page. If there is no section Entitled "History" in the
+ Document, create one stating the title, year, authors, and
+ publisher of the Document as given on its Title Page, then add
+ an item describing the Modified Version as stated in the
+ previous sentence.
+
+ J. Preserve the network location, if any, given in the Document
+ for public access to a Transparent copy of the Document, and
+ likewise the network locations given in the Document for
+ previous versions it was based on. These may be placed in the
+ "History" section. You may omit a network location for a work
+ that was published at least four years before the Document
+ itself, or if the original publisher of the version it refers
+ to gives permission.
+
+ K. For any section Entitled "Acknowledgements" or "Dedications",
+ Preserve the Title of the section, and preserve in the section
+ all the substance and tone of each of the contributor
+ acknowledgements and/or dedications given therein.
+
+ L. Preserve all the Invariant Sections of the Document, unaltered
+ in their text and in their titles. Section numbers or the
+ equivalent are not considered part of the section titles.
+
+ M. Delete any section Entitled "Endorsements". Such a section
+ may not be included in the Modified Version.
+
+ N. Do not retitle any existing section to be Entitled
+ "Endorsements" or to conflict in title with any Invariant
+ Section.
+
+ O. Preserve any Warranty Disclaimers.
+
+ If the Modified Version includes new front-matter sections or
+ appendices that qualify as Secondary Sections and contain no
+ material copied from the Document, you may at your option designate
+ some or all of these sections as invariant. To do this, add their
+ titles to the list of Invariant Sections in the Modified Version's
+ license notice. These titles must be distinct from any other
+ section titles.
+
+ You may add a section Entitled "Endorsements", provided it contains
+ nothing but endorsements of your Modified Version by various
+ parties--for example, statements of peer review or that the text
+ has been approved by an organization as the authoritative
+ definition of a standard.
+
+ You may add a passage of up to five words as a Front-Cover Text,
+ and a passage of up to 25 words as a Back-Cover Text, to the end of
+ the list of Cover Texts in the Modified Version. Only one passage
+ of Front-Cover Text and one of Back-Cover Text may be added by (or
+ through arrangements made by) any one entity. If the Document
+ already includes a cover text for the same cover, previously added
+ by you or by arrangement made by the same entity you are acting on
+ behalf of, you may not add another; but you may replace the old
+ one, on explicit permission from the previous publisher that added
+ the old one.
+
+ The author(s) and publisher(s) of the Document do not by this
+ License give permission to use their names for publicity for or to
+ assert or imply endorsement of any Modified Version.
+
+ 5. COMBINING DOCUMENTS
+
+ You may combine the Document with other documents released under
+ this License, under the terms defined in section 4 above for
+ modified versions, provided that you include in the combination all
+ of the Invariant Sections of all of the original documents,
+ unmodified, and list them all as Invariant Sections of your
+ combined work in its license notice, and that you preserve all
+ their Warranty Disclaimers.
+
+ The combined work need only contain one copy of this License, and
+ multiple identical Invariant Sections may be replaced with a single
+ copy. If there are multiple Invariant Sections with the same name
+ but different contents, make the title of each such section unique
+ by adding at the end of it, in parentheses, the name of the
+ original author or publisher of that section if known, or else a
+ unique number. Make the same adjustment to the section titles in
+ the list of Invariant Sections in the license notice of the
+ combined work.
+
+ In the combination, you must combine any sections Entitled
+ "History" in the various original documents, forming one section
+ Entitled "History"; likewise combine any sections Entitled
+ "Acknowledgements", and any sections Entitled "Dedications". You
+ must delete all sections Entitled "Endorsements."
+
+ 6. COLLECTIONS OF DOCUMENTS
+
+ You may make a collection consisting of the Document and other
+ documents released under this License, and replace the individual
+ copies of this License in the various documents with a single copy
+ that is included in the collection, provided that you follow the
+ rules of this License for verbatim copying of each of the documents
+ in all other respects.
+
+ You may extract a single document from such a collection, and
+ distribute it individually under this License, provided you insert
+ a copy of this License into the extracted document, and follow this
+ License in all other respects regarding verbatim copying of that
+ document.
+
+ 7. AGGREGATION WITH INDEPENDENT WORKS
+
+ A compilation of the Document or its derivatives with other
+ separate and independent documents or works, in or on a volume of a
+ storage or distribution medium, is called an "aggregate" if the
+ copyright resulting from the compilation is not used to limit the
+ legal rights of the compilation's users beyond what the individual
+ works permit. When the Document is included in an aggregate, this
+ License does not apply to the other works in the aggregate which
+ are not themselves derivative works of the Document.
+
+ If the Cover Text requirement of section 3 is applicable to these
+ copies of the Document, then if the Document is less than one half
+ of the entire aggregate, the Document's Cover Texts may be placed
+ on covers that bracket the Document within the aggregate, or the
+ electronic equivalent of covers if the Document is in electronic
+ form. Otherwise they must appear on printed covers that bracket
+ the whole aggregate.
+
+ 8. TRANSLATION
+
+ Translation is considered a kind of modification, so you may
+ distribute translations of the Document under the terms of section
+ 4. Replacing Invariant Sections with translations requires special
+ permission from their copyright holders, but you may include
+ translations of some or all Invariant Sections in addition to the
+ original versions of these Invariant Sections. You may include a
+ translation of this License, and all the license notices in the
+ Document, and any Warranty Disclaimers, provided that you also
+ include the original English version of this License and the
+ original versions of those notices and disclaimers. In case of a
+ disagreement between the translation and the original version of
+ this License or a notice or disclaimer, the original version will
+ prevail.
+
+ If a section in the Document is Entitled "Acknowledgements",
+ "Dedications", or "History", the requirement (section 4) to
+ Preserve its Title (section 1) will typically require changing the
+ actual title.
+
+ 9. TERMINATION
+
+ You may not copy, modify, sublicense, or distribute the Document
+ except as expressly provided under this License. Any attempt
+ otherwise to copy, modify, sublicense, or distribute it is void,
+ and will automatically terminate your rights under this License.
+
+ However, if you cease all violation of this License, then your
+ license from a particular copyright holder is reinstated (a)
+ provisionally, unless and until the copyright holder explicitly and
+ finally terminates your license, and (b) permanently, if the
+ copyright holder fails to notify you of the violation by some
+ reasonable means prior to 60 days after the cessation.
+
+ Moreover, your license from a particular copyright holder is
+ reinstated permanently if the copyright holder notifies you of the
+ violation by some reasonable means, this is the first time you have
+ received notice of violation of this License (for any work) from
+ that copyright holder, and you cure the violation prior to 30 days
+ after your receipt of the notice.
+
+ Termination of your rights under this section does not terminate
+ the licenses of parties who have received copies or rights from you
+ under this License. If your rights have been terminated and not
+ permanently reinstated, receipt of a copy of some or all of the
+ same material does not give you any rights to use it.
+
+ 10. FUTURE REVISIONS OF THIS LICENSE
+
+ The Free Software Foundation may publish new, revised versions of
+ the GNU Free Documentation License from time to time. Such new
+ versions will be similar in spirit to the present version, but may
+ differ in detail to address new problems or concerns. See
+ <http://www.gnu.org/copyleft/>.
+
+ Each version of the License is given a distinguishing version
+ number. If the Document specifies that a particular numbered
+ version of this License "or any later version" applies to it, you
+ have the option of following the terms and conditions either of
+ that specified version or of any later version that has been
+ published (not as a draft) by the Free Software Foundation. If the
+ Document does not specify a version number of this License, you may
+ choose any version ever published (not as a draft) by the Free
+ Software Foundation. If the Document specifies that a proxy can
+ decide which future versions of this License can be used, that
+ proxy's public statement of acceptance of a version permanently
+ authorizes you to choose that version for the Document.
+
+ 11. RELICENSING
+
+ "Massive Multiauthor Collaboration Site" (or "MMC Site") means any
+ World Wide Web server that publishes copyrightable works and also
+ provides prominent facilities for anybody to edit those works. A
+ public wiki that anybody can edit is an example of such a server.
+ A "Massive Multiauthor Collaboration" (or "MMC") contained in the
+ site means any set of copyrightable works thus published on the MMC
+ site.
+
+ "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
+ license published by Creative Commons Corporation, a not-for-profit
+ corporation with a principal place of business in San Francisco,
+ California, as well as future copyleft versions of that license
+ published by that same organization.
+
+ "Incorporate" means to publish or republish a Document, in whole or
+ in part, as part of another Document.
+
+ An MMC is "eligible for relicensing" if it is licensed under this
+ License, and if all works that were first published under this
+ License somewhere other than this MMC, and subsequently
+ incorporated in whole or in part into the MMC, (1) had no cover
+ texts or invariant sections, and (2) were thus incorporated prior
+ to November 1, 2008.
+
+ The operator of an MMC Site may republish an MMC contained in the
+ site under CC-BY-SA on the same site at any time before August 1,
+ 2009, provided the MMC is eligible for relicensing.
+
+ADDENDUM: How to use this License for your documents
+====================================================
+
+To use this License in a document you have written, include a copy of
+the License in the document and put the following copyright and license
+notices just after the title page:
+
+ Copyright (C) YEAR YOUR NAME.
+ Permission is granted to copy, distribute and/or modify this document
+ under the terms of the GNU Free Documentation License, Version 1.3
+ or any later version published by the Free Software Foundation;
+ with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
+ Texts. A copy of the license is included in the section entitled ``GNU
+ Free Documentation License''.
+
+ If you have Invariant Sections, Front-Cover Texts and Back-Cover
+Texts, replace the "with...Texts." line with this:
+
+ with the Invariant Sections being LIST THEIR TITLES, with
+ the Front-Cover Texts being LIST, and with the Back-Cover Texts
+ being LIST.
+
+ If you have Invariant Sections without Cover Texts, or some other
+combination of the three, merge those two alternatives to suit the
+situation.
+
+ If your document contains nontrivial examples of program code, we
+recommend releasing these examples in parallel under your choice of free
+software license, such as the GNU General Public License, to permit
+their use in free software.
+
+
+File: diffutils.info-t, Node: Translations, Next: Index, Prev: Copying This Manual, Up: Top
+
+Appendix B Translations of This Manual
+**************************************
+
+Nishio Futoshi of the GNUjdoc project has prepared a Japanese
+translation of this manual. Its most recent version can be found at
+<http://openlab.ring.gr.jp/gnujdoc/cvsweb/cvsweb.cgi/gnujdoc/>.
+
+
+File: diffutils.info-t, Node: Index, Prev: Translations, Up: Top
+
+Appendix C Index
+****************
+
+
+* Menu:
+
+* ! output format: Context. (line 6)
+* +- output format: Unified Format. (line 6)
+* < output format: Normal. (line 6)
+* <<<<<<< for marking conflicts: Marking Conflicts. (line 6)
+* _POSIX2_VERSION: Standards conformance.
+ (line 23)
+* ad capability: diff Options. (line 179)
+* aligning tab stops: Tabs. (line 6)
+* alternate file names: Alternate Names. (line 6)
+* always color option: diff Options. (line 43)
+* auto color option: diff Options. (line 42)
+* backup file names: Backup Names. (line 6)
+* backup file strategy: Backups. (line 6)
+* binary file diff: Binary. (line 6)
+* blank and tab difference suppression: White Space. (line 6)
+* blank line difference suppression: Blank Lines. (line 6)
+* brief difference reports: Brief. (line 6)
+* bug reports: Bugs. (line 6)
+* C function headings: C Function Headings. (line 6)
+* C if-then-else output format: If-then-else. (line 6)
+* case difference suppression: Case Folding. (line 6)
+* ClearCase: Revision Control. (line 6)
+* cmp invocation: Invoking cmp. (line 6)
+* cmp options: cmp Options. (line 6)
+* color, distinguishing different context: diff Options. (line 37)
+* columnar output: Side by Side. (line 6)
+* common mistakes with patches: Avoiding Common Mistakes.
+ (line 6)
+* comparing three files: Comparing Three Files.
+ (line 6)
+* conflict: diff3 Merging. (line 26)
+* conflict marking: Marking Conflicts. (line 6)
+* context output format: Context. (line 6)
+* creating files: Creating and Removing.
+ (line 6)
+* de capability: diff Options. (line 184)
+* diagnostics from patch: patch Messages. (line 6)
+* diff invocation: Invoking diff. (line 6)
+* diff merging: Interactive Merging. (line 6)
+* diff options: diff Options. (line 6)
+* diff sample input: Sample diff Input. (line 6)
+* diff3 hunks: diff3 Hunks. (line 6)
+* diff3 invocation: Invoking diff3. (line 6)
+* diff3 options: diff3 Options. (line 6)
+* diff3 sample input: Sample diff3 Input. (line 6)
+* directories and patch: patch Directories. (line 6)
+* directory structure changes: Changing Structure. (line 6)
+* dry runs for patch: Dry Runs. (line 6)
+* ed script output format: ed Scripts. (line 6)
+* EDITOR: Merge Commands. (line 50)
+* empty files, removing: Creating and Removing.
+ (line 6)
+* exabyte, definition of: cmp Options. (line 99)
+* exbibyte, definition of: cmp Options. (line 102)
+* file name alternates: Alternate Names. (line 6)
+* file names with unusual characters: Unusual File Names. (line 6)
+* format of diff output: Output Formats. (line 6)
+* format of diff3 output: Comparing Three Files.
+ (line 6)
+* formats for if-then-else line groups: Line Group Formats. (line 6)
+* forward ed script output format: Forward ed. (line 6)
+* full lines: Incomplete Lines. (line 6)
+* function headings, C: C Function Headings. (line 6)
+* fuzz factor when patching: Inexact. (line 6)
+* gibibyte, definition of: cmp Options. (line 87)
+* gigabyte, definition of: cmp Options. (line 84)
+* hd capability: diff Options. (line 189)
+* headings: Sections. (line 6)
+* hunks: Hunks. (line 6)
+* hunks for diff3: diff3 Hunks. (line 6)
+* if-then-else output format: If-then-else. (line 6)
+* ifdef output format: If-then-else. (line 6)
+* imperfect patch application: Imperfect. (line 6)
+* incomplete line merging: Merging Incomplete Lines.
+ (line 6)
+* incomplete lines: Incomplete Lines. (line 6)
+* inexact patches: Inexact. (line 6)
+* inhibit messages from patch: More or Fewer Messages.
+ (line 6)
+* interactive merging: Interactive Merging. (line 6)
+* introduction: Comparison. (line 6)
+* intuiting file names from patches: Multiple Patches. (line 6)
+* invoking cmp: Invoking cmp. (line 6)
+* invoking diff: Invoking diff. (line 6)
+* invoking diff3: Invoking diff3. (line 6)
+* invoking patch: Invoking patch. (line 6)
+* invoking sdiff: Invoking sdiff. (line 6)
+* keyboard input to patch: patch and Keyboard Input.
+ (line 6)
+* kibibyte, definition of: cmp Options. (line 75)
+* kilobyte, definition of: cmp Options. (line 71)
+* LC_COLLATE: Comparing Directories.
+ (line 6)
+* LC_NUMERIC: Line Group Formats. (line 143)
+* LC_TIME: Detailed Context. (line 12)
+* line formats: Line Formats. (line 6)
+* line group formats: Line Group Formats. (line 6)
+* ln capability: diff Options. (line 194)
+* mebibyte, definition of: cmp Options. (line 82)
+* megabyte, definition of: cmp Options. (line 79)
+* merge commands: Merge Commands. (line 6)
+* merged diff3 format: Bypassing ed. (line 6)
+* merged output format: If-then-else. (line 6)
+* merging from a common ancestor: diff3 Merging. (line 6)
+* merging interactively: Merge Commands. (line 6)
+* messages from patch: patch Messages. (line 6)
+* multibyte characters: Internationalization.
+ (line 6)
+* multiple patches: Multiple Patches. (line 6)
+* newline treatment by diff: Incomplete Lines. (line 6)
+* none color option: diff Options. (line 40)
+* normal output format: Normal. (line 6)
+* options for cmp: cmp Options. (line 6)
+* options for diff: diff Options. (line 6)
+* options for diff3: diff3 Options. (line 6)
+* options for patch: patch Options. (line 6)
+* options for sdiff: sdiff Options. (line 6)
+* output formats: Output Formats. (line 6)
+* overlap: diff3 Merging. (line 26)
+* overlapping change, selection of: Which Changes. (line 6)
+* overview of diff and patch: Overview. (line 6)
+* paginating diff output: Pagination. (line 6)
+* patch consumer tips: Tips for Patch Consumers.
+ (line 6)
+* patch input format: patch Input. (line 6)
+* patch invocation: Invoking patch. (line 6)
+* patch messages and questions: patch Messages. (line 6)
+* patch options: patch Options. (line 6)
+* patch producer tips: Tips for Patch Producers.
+ (line 6)
+* patch, common mistakes: Avoiding Common Mistakes.
+ (line 6)
+* patches, shrinking: Generating Smaller Patches.
+ (line 6)
+* patching directories: patch Directories. (line 6)
+* PATCH_GET: Revision Control. (line 13)
+* PATCH_VERSION_CONTROL: Backup Names. (line 21)
+* pebibyte, definition of: cmp Options. (line 97)
+* performance of diff: diff Performance. (line 6)
+* petabyte, definition of: cmp Options. (line 94)
+* POSIX: patch and POSIX. (line 6)
+* POSIX <1>: Standards conformance.
+ (line 6)
+* POSIXLY_CORRECT: patch and POSIX. (line 6)
+* POSIXLY_CORRECT <1>: Standards conformance.
+ (line 6)
+* projects for directories: Shortcomings. (line 6)
+* quoting style: patch Quoting Style. (line 6)
+* QUOTING_STYLE: patch Quoting Style. (line 26)
+* RCS: Revision Control. (line 6)
+* RCS script output format: RCS. (line 6)
+* regular expression matching headings: Specified Headings. (line 6)
+* regular expression suppression: Specified Lines. (line 6)
+* reject file names: Reject Names. (line 6)
+* removing empty files: Creating and Removing.
+ (line 6)
+* reporting bugs: Bugs. (line 6)
+* reversed patches: Reversed Patches. (line 6)
+* revision control: Revision Control. (line 6)
+* sample input for diff: Sample diff Input. (line 6)
+* sample input for diff3: Sample diff3 Input. (line 6)
+* SCCS: Revision Control. (line 6)
+* script output formats: Scripts. (line 6)
+* sdiff invocation: Invoking sdiff. (line 6)
+* sdiff options: sdiff Options. (line 6)
+* sdiff output format: sdiff Option Summary.
+ (line 6)
+* section headings: Sections. (line 6)
+* side by side: Side by Side. (line 6)
+* side by side format: Side by Side Format. (line 6)
+* SIMPLE_BACKUP_SUFFIX: Backup Names. (line 12)
+* special files: Special Files. (line 6)
+* specified headings: Specified Headings. (line 6)
+* summarizing which files differ: Brief. (line 6)
+* System V diff3 compatibility: Saving the Changed File.
+ (line 6)
+* tab and blank difference suppression: White Space. (line 6)
+* tab stop alignment: Tabs. (line 6)
+* tebibyte, definition of: cmp Options. (line 92)
+* terabyte, definition of: cmp Options. (line 89)
+* terminal, using color iff: diff Options. (line 42)
+* testing patch: Dry Runs. (line 6)
+* text versus binary diff: Binary. (line 6)
+* time stamp format, context diffs: Detailed Context. (line 12)
+* time stamp format, unified diffs: Detailed Unified. (line 12)
+* time stamps on patched files: Patching Time Stamps.
+ (line 6)
+* traditional patch: patch and Tradition. (line 6)
+* trailing blanks: Trailing Blanks. (line 6)
+* two-column output: Side by Side. (line 6)
+* unified output format: Unified Format. (line 6)
+* unmerged change: Which Changes. (line 6)
+* varying-width characters: Internationalization.
+ (line 6)
+* verbose messages from patch: More or Fewer Messages.
+ (line 6)
+* version control: Revision Control. (line 6)
+* VERSION_CONTROL: Revision Control. (line 22)
+* VERSION_CONTROL <1>: Backup Names. (line 21)
+* white space in patches: Changed White Space. (line 6)
+* yottabyte, definition of: cmp Options. (line 110)
+* zettabyte, definition of: cmp Options. (line 104)
+
+
+
+Tag Table:
+Node: Top1432
+Node: Overview3646
+Node: Comparison7200
+Node: Hunks10144
+Node: White Space11587
+Node: Blank Lines13428
+Node: Specified Lines14419
+Node: Case Folding15547
+Node: Brief15966
+Node: Binary17291
+Node: Output Formats21090
+Node: Sample diff Input21817
+Node: Context23318
+Node: Context Format24897
+Node: Example Context25691
+Node: Less Context27201
+Node: Detailed Context28393
+Node: Unified Format30593
+Node: Example Unified31392
+Node: Detailed Unified32432
+Node: Sections34076
+Node: Specified Headings34837
+Node: C Function Headings36388
+Node: Alternate Names37236
+Node: Side by Side38151
+Node: Side by Side Format40303
+Node: Example Side by Side41207
+Node: Normal42549
+Node: Example Normal43552
+Node: Detailed Normal44291
+Node: Scripts46032
+Node: ed Scripts46439
+Node: Example ed47647
+Node: Detailed ed48099
+Node: Forward ed49860
+Node: RCS50638
+Node: If-then-else51856
+Node: Line Group Formats53536
+Node: Line Formats59419
+Node: Example If-then-else62690
+Node: Detailed If-then-else63771
+Node: Incomplete Lines65658
+Node: Comparing Directories67296
+Node: Adjusting Output71590
+Node: Tabs72099
+Node: Trailing Blanks73715
+Node: Pagination74942
+Node: diff Performance75412
+Node: Comparing Three Files78503
+Node: Sample diff3 Input79383
+Node: Example diff3 Normal80333
+Node: Detailed diff3 Normal81399
+Node: diff3 Hunks83189
+Node: diff3 Merging84457
+Node: Which Changes86704
+Node: Marking Conflicts88106
+Node: Bypassing ed90563
+Node: Merging Incomplete Lines91908
+Node: Saving the Changed File92636
+Node: Interactive Merging93254
+Node: sdiff Option Summary93965
+Node: Merge Commands95170
+Node: Merging with patch96461
+Node: patch Input98832
+Node: Revision Control99516
+Node: Imperfect100689
+Node: Changed White Space101840
+Node: Reversed Patches102639
+Node: Inexact104105
+Node: Dry Runs107663
+Node: Creating and Removing108529
+Node: Patching Time Stamps109581
+Node: Multiple Patches111782
+Node: patch Directories114446
+Node: Backups116072
+Node: Backup Names117139
+Ref: Backup Names-Footnote-1120096
+Node: Reject Names120223
+Node: patch Messages120814
+Node: More or Fewer Messages121876
+Node: patch and Keyboard Input122509
+Node: patch Quoting Style123540
+Node: patch and POSIX124688
+Node: patch and Tradition125529
+Node: Making Patches128953
+Node: Tips for Patch Producers129781
+Node: Tips for Patch Consumers131039
+Node: Avoiding Common Mistakes131678
+Node: Generating Smaller Patches134205
+Node: Invoking cmp135967
+Node: cmp Options137391
+Node: Invoking diff141037
+Node: diff Options142658
+Node: Invoking diff3152509
+Node: diff3 Options153149
+Node: Invoking patch156184
+Node: patch Options157394
+Node: Invoking sdiff162623
+Node: sdiff Options163767
+Node: Standards conformance166741
+Node: Projects168489
+Node: Shortcomings169203
+Node: Internationalization170307
+Node: Changing Structure171475
+Node: Special Files172581
+Node: Unusual File Names173694
+Node: Time Stamp Order174335
+Node: Ignoring Changes174980
+Node: Speedups175752
+Node: Bugs176218
+Node: Copying This Manual177073
+Node: Translations202194
+Node: Index202568
+
+End Tag Table
diff --git a/doc/diffutils.texi b/doc/diffutils.texi
new file mode 100644
index 0000000..b478380
--- /dev/null
+++ b/doc/diffutils.texi
@@ -0,0 +1,4759 @@
+\input texinfo @c -*-texinfo-*-
+@comment %**start of header
+@setfilename diffutils.info
+@include version.texi
+@settitle Comparing and Merging Files
+@syncodeindex vr cp
+@setchapternewpage odd
+@comment %**end of header
+@copying
+This manual is for GNU Diffutils
+(version @value{VERSION}, @value{UPDATED}),
+and documents the @acronym{GNU} @command{diff}, @command{diff3},
+@command{sdiff}, and @command{cmp} commands for showing the
+differences between files and the @acronym{GNU} @command{patch} command for
+using their output to update files.
+
+Copyright @copyright{} 1992-1994, 1998, 2001-2002, 2004, 2006, 2009-2016 Free
+Software Foundation, Inc.
+
+@quotation
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
+A copy of the license is included in the section entitled
+``@acronym{GNU} Free Documentation License.''
+@end quotation
+@end copying
+
+@c Debian install-info (up through at least version 1.9.20) uses only the
+@c first dircategory. Put this one first, as it is more useful in practice.
+@dircategory Individual utilities
+@direntry
+* cmp: (diffutils)Invoking cmp. Compare 2 files byte by byte.
+* diff: (diffutils)Invoking diff. Compare 2 files line by line.
+* diff3: (diffutils)Invoking diff3. Compare 3 files line by line.
+* patch: (diffutils)Invoking patch. Apply a patch to a file.
+* sdiff: (diffutils)Invoking sdiff. Merge 2 files side-by-side.
+@end direntry
+
+@dircategory Text creation and manipulation
+@direntry
+* Diffutils: (diffutils). Comparing and merging files.
+@end direntry
+
+@titlepage
+@title Comparing and Merging Files
+@subtitle for Diffutils @value{VERSION} and @code{patch} 2.5.4
+@subtitle @value{UPDATED}
+@author David MacKenzie, Paul Eggert, and Richard Stallman
+@page
+@vskip 0pt plus 1filll
+@insertcopying
+@end titlepage
+
+@shortcontents
+@contents
+
+@ifnottex
+@node Top
+@top Comparing and Merging Files
+
+@insertcopying
+@end ifnottex
+
+@menu
+* Overview:: Preliminary information.
+* Comparison:: What file comparison means.
+
+* Output Formats:: Formats for two-way difference reports.
+* Incomplete Lines:: Lines that lack trailing newlines.
+* Comparing Directories:: Comparing files and directories.
+* Adjusting Output:: Making @command{diff} output prettier.
+* diff Performance:: Making @command{diff} smarter or faster.
+
+* Comparing Three Files:: Formats for three-way difference reports.
+* diff3 Merging:: Merging from a common ancestor.
+
+* Interactive Merging:: Interactive merging with @command{sdiff}.
+
+* Merging with patch:: Using @command{patch} to change old files into new ones.
+* Making Patches:: Tips for making and using patch distributions.
+
+* Invoking cmp:: Compare two files byte by byte.
+* Invoking diff:: Compare two files line by line.
+* Invoking diff3:: Compare three files line by line.
+* Invoking patch:: Apply a diff file to an original.
+* Invoking sdiff:: Side-by-side merge of file differences.
+
+* Standards conformance:: Conformance to the @acronym{POSIX} standard.
+* Projects:: If you've found a bug or other shortcoming.
+
+* Copying This Manual:: How to make copies of this manual.
+* Translations:: Available translations of this manual.
+* Index:: Index.
+@end menu
+
+@node Overview
+@unnumbered Overview
+@cindex overview of @command{diff} and @command{patch}
+
+Computer users often find occasion to ask how two files differ. Perhaps
+one file is a newer version of the other file. Or maybe the two files
+started out as identical copies but were changed by different people.
+
+You can use the @command{diff} command to show differences between two
+files, or each corresponding file in two directories. @command{diff}
+outputs differences between files line by line in any of several
+formats, selectable by command line options. This set of differences is
+often called a @dfn{diff} or @dfn{patch}. For files that are identical,
+@command{diff} normally produces no output; for binary (non-text) files,
+@command{diff} normally reports only that they are different.
+
+You can use the @command{cmp} command to show the byte and line numbers
+where two files differ. @command{cmp} can also show all the bytes
+that differ between the two files, side by side. A way to compare
+two files character by character is the Emacs command @kbd{M-x
+compare-windows}. @xref{Other Window, , Other Window, emacs, The @acronym{GNU}
+Emacs Manual}, for more information on that command.
+
+You can use the @command{diff3} command to show differences among three
+files. When two people have made independent changes to a common
+original, @command{diff3} can report the differences between the original
+and the two changed versions, and can produce a merged file that
+contains both persons' changes together with warnings about conflicts.
+
+You can use the @command{sdiff} command to merge two files interactively.
+
+You can use the set of differences produced by @command{diff} to distribute
+updates to text files (such as program source code) to other people.
+This method is especially useful when the differences are small compared
+to the complete files. Given @command{diff} output, you can use the
+@command{patch} program to update, or @dfn{patch}, a copy of the file. If you
+think of @command{diff} as subtracting one file from another to produce
+their difference, you can think of @command{patch} as adding the difference
+to one file to reproduce the other.
+
+This manual first concentrates on making diffs, and later shows how to
+use diffs to update files.
+
+@acronym{GNU} @command{diff} was written by Paul Eggert, Mike Haertel,
+David Hayes, Richard Stallman, and Len Tower. Wayne Davison designed and
+implemented the unified output format. The basic algorithm is described
+by Eugene W. Myers in ``An O(ND) Difference Algorithm and its Variations'',
+@cite{Algorithmica} Vol.@: 1, 1986, pp.@: 251--266,
+@url{http://dx.doi.org/10.1007/BF01840446}; and in ``A File
+Comparison Program'', Webb Miller and Eugene W. Myers,
+@cite{Software---Practice and Experience} Vol.@: 15, 1985,
+pp.@: 1025--1040,
+@url{http://dx.doi.org/10.1002/spe.4380151102}.
+@c From: "Gene Myers" <gene@cs.arizona.edu>
+@c They are about the same basic algorithm; the Algorithmica
+@c paper gives a rigorous treatment and the sub-algorithm for
+@c delivering scripts and should be the primary reference, but
+@c both should be mentioned.
+The algorithm was independently discovered as described by Esko Ukkonen in
+``Algorithms for Approximate String Matching'',
+@cite{Information and Control} Vol.@: 64, 1985, pp.@: 100--118,
+@url{http://dx.doi.org/10.1016/S0019-9958(85)80046-2}.
+@c From: "Gene Myers" <gene@cs.arizona.edu>
+@c Date: Wed, 29 Sep 1993 08:27:55 MST
+@c Ukkonen should be given credit for also discovering the algorithm used
+@c in GNU diff.
+Related algorithms are surveyed by Alfred V. Aho in
+section 6.3 of ``Algorithms for Finding Patterns in Strings'',
+@cite{Handbook of Theoretical Computer Science} (Jan Van Leeuwen,
+ed.), Vol.@: A, @cite{Algorithms and Complexity}, Elsevier/MIT Press,
+1990, pp.@: 255--300.
+
+@acronym{GNU} @command{diff3} was written by Randy Smith. @acronym{GNU}
+@command{sdiff} was written by Thomas Lord. @acronym{GNU} @command{cmp}
+was written by Torbj@"orn Granlund and David MacKenzie.
+
+@acronym{GNU} @command{patch} was written mainly by Larry Wall and Paul Eggert;
+several @acronym{GNU} enhancements were contributed by Wayne Davison and
+David MacKenzie. Parts of this manual are adapted from a manual page
+written by Larry Wall, with his permission.
+
+@node Comparison
+@chapter What Comparison Means
+@cindex introduction
+
+There are several ways to think about the differences between two files.
+One way to think of the differences is as a series of lines that were
+deleted from, inserted in, or changed in one file to produce the other
+file. @command{diff} compares two files line by line, finds groups of
+lines that differ, and reports each group of differing lines. It can
+report the differing lines in several formats, which have different
+purposes.
+
+@acronym{GNU} @command{diff} can show whether files are different
+without detailing the differences. It also provides ways to suppress
+certain kinds of differences that are not important to you. Most
+commonly, such differences are changes in the amount of white space
+between words or lines. @command{diff} also provides ways to suppress
+differences in alphabetic case or in lines that match a regular
+expression that you provide. These options can accumulate; for
+example, you can ignore changes in both white space and alphabetic
+case.
+
+Another way to think of the differences between two files is as a
+sequence of pairs of bytes that can be either identical or
+different. @command{cmp} reports the differences between two files
+byte by byte, instead of line by line. As a result, it is often
+more useful than @command{diff} for comparing binary files. For text
+files, @command{cmp} is useful mainly when you want to know only whether
+two files are identical, or whether one file is a prefix of the other.
+
+To illustrate the effect that considering changes byte by byte
+can have compared with considering them line by line, think of what
+happens if a single newline character is added to the beginning of a
+file. If that file is then compared with an otherwise identical file
+that lacks the newline at the beginning, @command{diff} will report that a
+blank line has been added to the file, while @command{cmp} will report that
+almost every byte of the two files differs.
+
+@command{diff3} normally compares three input files line by line, finds
+groups of lines that differ, and reports each group of differing lines.
+Its output is designed to make it easy to inspect two different sets of
+changes to the same file.
+
+These commands compare input files without necessarily reading them.
+For example, if @command{diff} is asked simply to report whether two
+files differ, and it discovers that the files have different sizes, it
+need not read them to do its job.
+
+@menu
+* Hunks:: Groups of differing lines.
+* White Space:: Suppressing differences in white space.
+* Blank Lines:: Suppressing differences whose lines are all blank.
+* Specified Lines:: Suppressing differences whose lines all match a pattern.
+* Case Folding:: Suppressing differences in alphabetic case.
+* Brief:: Summarizing which files are different.
+* Binary:: Comparing binary files or forcing text comparisons.
+@end menu
+
+@node Hunks
+@section Hunks
+@cindex hunks
+
+When comparing two files, @command{diff} finds sequences of lines common to
+both files, interspersed with groups of differing lines called
+@dfn{hunks}. Comparing two identical files yields one sequence of
+common lines and no hunks, because no lines differ. Comparing two
+entirely different files yields no common lines and one large hunk that
+contains all lines of both files. In general, there are many ways to
+match up lines between two given files. @command{diff} tries to minimize
+the total hunk size by finding large sequences of common lines
+interspersed with small hunks of differing lines.
+
+For example, suppose the file @file{F} contains the three lines
+@samp{a}, @samp{b}, @samp{c}, and the file @file{G} contains the same
+three lines in reverse order @samp{c}, @samp{b}, @samp{a}. If
+@command{diff} finds the line @samp{c} as common, then the command
+@samp{diff F G} produces this output:
+
+@example
+1,2d0
+< a
+< b
+3a2,3
+> b
+> a
+@end example
+
+@noindent
+But if @command{diff} notices the common line @samp{b} instead, it produces
+this output:
+
+@example
+1c1
+< a
+---
+> c
+3c3
+< c
+---
+> a
+@end example
+
+@noindent
+It is also possible to find @samp{a} as the common line. @command{diff}
+does not always find an optimal matching between the files; it takes
+shortcuts to run faster. But its output is usually close to the
+shortest possible. You can adjust this tradeoff with the
+@option{--minimal} (@option{-d}) option (@pxref{diff Performance}).
+
+@node White Space
+@section Suppressing Differences in Blank and Tab Spacing
+@cindex blank and tab difference suppression
+@cindex tab and blank difference suppression
+
+The @option{--ignore-tab-expansion} (@option{-E}) option ignores the
+distinction between tabs and spaces on input. A tab is considered to be
+equivalent to the number of spaces to the next tab stop (@pxref{Tabs}).
+
+The @option{--ignore-trailing-space} (@option{-Z}) option ignores white
+space at line end.
+
+The @option{--ignore-space-change} (@option{-b}) option is stronger than
+@option{-E} and @option{-Z} combined.
+It ignores white space at line end, and considers all other sequences of
+one or more white space characters within a line to be equivalent. With this
+option, @command{diff} considers the following two lines to be equivalent,
+where @samp{$} denotes the line end:
+
+@example
+Here lyeth muche rychnesse in lytell space. -- John Heywood$
+Here lyeth muche rychnesse in lytell space. -- John Heywood $
+@end example
+
+The @option{--ignore-all-space} (@option{-w}) option is stronger still.
+It ignores differences even if one line has white space where
+the other line has none. @dfn{White space} characters include
+tab, vertical tab, form feed, carriage return, and space;
+some locales may define additional characters to be white space.
+With this option, @command{diff} considers the
+following two lines to be equivalent, where @samp{$} denotes the line
+end and @samp{^M} denotes a carriage return:
+
+@example
+Here lyeth muche rychnesse in lytell space.-- John Heywood$
+ He relyeth much erychnes seinly tells pace. --John Heywood ^M$
+@end example
+
+For many other programs newline is also a white space character, but
+@command{diff} is a line-oriented program and a newline character
+always ends a line. Hence the @option{-w} or
+@option{--ignore-all-space} option does not ignore newline-related
+changes; it ignores only other white space changes.
+
+@node Blank Lines
+@section Suppressing Differences Whose Lines Are All Blank
+@cindex blank line difference suppression
+
+The @option{--ignore-blank-lines} (@option{-B}) option ignores changes
+that consist entirely of blank lines. With this option, for example, a
+file containing
+@example
+1. A point is that which has no part.
+
+2. A line is breadthless length.
+-- Euclid, The Elements, I
+@end example
+@noindent
+is considered identical to a file containing
+@example
+1. A point is that which has no part.
+2. A line is breadthless length.
+
+
+-- Euclid, The Elements, I
+@end example
+
+Normally this option affects only lines that are completely empty, but
+if you also specify an option that ignores trailing spaces,
+lines are also affected if they look empty but contain white space.
+In other words, @option{-B} is equivalent to @samp{-I '^$'} by
+default, but it is equivalent to @option{-I '^[[:space:]]*$'} if
+@option{-b}, @option{-w} or @option{-Z} is also specified.
+
+@node Specified Lines
+@section Suppressing Differences Whose Lines All Match a Regular Expression
+@cindex regular expression suppression
+
+To ignore insertions and deletions of lines that match a
+@command{grep}-style regular expression, use the
+@option{--ignore-matching-lines=@var{regexp}} (@option{-I @var{regexp}}) option.
+You should escape
+regular expressions that contain shell metacharacters to prevent the
+shell from expanding them. For example, @samp{diff -I '^[[:digit:]]'} ignores
+all changes to lines beginning with a digit.
+
+However, @option{-I} only ignores the insertion or deletion of lines that
+contain the regular expression if every changed line in the hunk---every
+insertion and every deletion---matches the regular expression. In other
+words, for each nonignorable change, @command{diff} prints the complete set
+of changes in its vicinity, including the ignorable ones.
+
+You can specify more than one regular expression for lines to ignore by
+using more than one @option{-I} option. @command{diff} tries to match each
+line against each regular expression.
+
+@node Case Folding
+@section Suppressing Case Differences
+@cindex case difference suppression
+
+@acronym{GNU} @command{diff} can treat lower case letters as
+equivalent to their upper case counterparts, so that, for example, it
+considers @samp{Funky Stuff}, @samp{funky STUFF}, and @samp{fUNKy
+stuFf} to all be the same. To request this, use the @option{-i} or
+@option{--ignore-case} option.
+
+@node Brief
+@section Summarizing Which Files Differ
+@cindex summarizing which files differ
+@cindex brief difference reports
+
+When you only want to find out whether files are different, and you
+don't care what the differences are, you can use the summary output
+format. In this format, instead of showing the differences between the
+files, @command{diff} simply reports whether files differ. The
+@option{--brief} (@option{-q}) option selects this output format.
+
+This format is especially useful when comparing the contents of two
+directories. It is also much faster than doing the normal line by line
+comparisons, because @command{diff} can stop analyzing the files as soon as
+it knows that there are any differences.
+
+You can also get a brief indication of whether two files differ by using
+@command{cmp}. For files that are identical, @command{cmp} produces no
+output. When the files differ, by default, @command{cmp} outputs the byte
+and line number where the first difference occurs, or reports that one
+file is a prefix of the other. You can use
+the @option{-s}, @option{--quiet}, or @option{--silent} option to
+suppress that information, so that @command{cmp}
+produces no output and reports whether the files differ using only its
+exit status (@pxref{Invoking cmp}).
+
+@c Fix this.
+Unlike @command{diff}, @command{cmp} cannot compare directories; it can only
+compare two files.
+
+@node Binary
+@section Binary Files and Forcing Text Comparisons
+@cindex binary file diff
+@cindex text versus binary diff
+
+If @command{diff} thinks that either of the two files it is comparing is
+binary (a non-text file), it normally treats that pair of files much as
+if the summary output format had been selected (@pxref{Brief}), and
+reports only that the binary files are different. This is because line
+by line comparisons are usually not meaningful for binary files.
+This does not count as trouble, even though the resulting output does
+not capture all the differences.
+
+@command{diff} determines whether a file is text or binary by checking the
+first few bytes in the file; the exact number of bytes is system
+dependent, but it is typically several thousand. If every byte in
+that part of the file is non-null, @command{diff} considers the file to be
+text; otherwise it considers the file to be binary.
+
+Sometimes you might want to force @command{diff} to consider files to be
+text. For example, you might be comparing text files that contain
+null characters; @command{diff} would erroneously decide that those are
+non-text files. Or you might be comparing documents that are in a
+format used by a word processing system that uses null characters to
+indicate special formatting. You can force @command{diff} to consider all
+files to be text files, and compare them line by line, by using the
+@option{--text} (@option{-a}) option. If the files you compare using this
+option do not in fact contain text, they will probably contain few
+newline characters, and the @command{diff} output will consist of hunks
+showing differences between long lines of whatever characters the files
+contain.
+
+You can also force @command{diff} to report only whether files differ
+(but not how). Use the @option{--brief} (@option{-q}) option for
+this.
+
+In operating systems that distinguish between text and binary files,
+@command{diff} normally reads and writes all data as text. Use the
+@option{--binary} option to force @command{diff} to read and write binary
+data instead. This option has no effect on a @acronym{POSIX}-compliant system
+like @acronym{GNU} or traditional Unix. However, many personal computer
+operating systems represent the end of a line with a carriage return
+followed by a newline. On such systems, @command{diff} normally ignores
+these carriage returns on input and generates them at the end of each
+output line, but with the @option{--binary} option @command{diff} treats
+each carriage return as just another input character, and does not
+generate a carriage return at the end of each output line. This can be
+useful when dealing with non-text files that are meant to be
+interchanged with @acronym{POSIX}-compliant systems.
+
+The @option{--strip-trailing-cr} causes @command{diff} to treat input
+lines that end in carriage return followed by newline as if they end
+in plain newline. This can be useful when comparing text that is
+imperfectly imported from many personal computer operating systems.
+This option affects how lines are read, which in turn affects how they
+are compared and output.
+
+If you want to compare two files byte by byte, you can use the
+@command{cmp} program with the @option{--verbose} (@option{-l})
+option to show the values of each differing byte in the two files.
+With @acronym{GNU} @command{cmp}, you can also use the @option{-b} or
+@option{--print-bytes} option to show the @acronym{ASCII} representation of
+those bytes. @xref{Invoking cmp}, for more information.
+
+If @command{diff3} thinks that any of the files it is comparing is binary
+(a non-text file), it normally reports an error, because such
+comparisons are usually not useful. @command{diff3} uses the same test as
+@command{diff} to decide whether a file is binary. As with @command{diff}, if
+the input files contain a few non-text bytes but otherwise are like
+text files, you can force @command{diff3} to consider all files to be text
+files and compare them line by line by using the @option{-a} or
+@option{--text} option.
+
+@node Output Formats
+@chapter @command{diff} Output Formats
+@cindex output formats
+@cindex format of @command{diff} output
+
+@command{diff} has several mutually exclusive options for output format.
+The following sections describe each format, illustrating how
+@command{diff} reports the differences between two sample input files.
+
+@menu
+* Sample diff Input:: Sample @command{diff} input files for examples.
+* Context:: Showing differences with the surrounding text.
+* Side by Side:: Showing differences in two columns.
+* Normal:: Showing differences without surrounding text.
+* Scripts:: Generating scripts for other programs.
+* If-then-else:: Merging files with if-then-else.
+@end menu
+
+@node Sample diff Input
+@section Two Sample Input Files
+@cindex @command{diff} sample input
+@cindex sample input for @command{diff}
+
+Here are two sample files that we will use in numerous examples to
+illustrate the output of @command{diff} and how various options can change
+it.
+
+This is the file @file{lao}:
+
+@example
+The Way that can be told of is not the eternal Way;
+The name that can be named is not the eternal name.
+The Nameless is the origin of Heaven and Earth;
+The Named is the mother of all things.
+Therefore let there always be non-being,
+ so we may see their subtlety,
+And let there always be being,
+ so we may see their outcome.
+The two are the same,
+But after they are produced,
+ they have different names.
+@end example
+
+This is the file @file{tzu}:
+
+@example
+The Nameless is the origin of Heaven and Earth;
+The named is the mother of all things.
+
+Therefore let there always be non-being,
+ so we may see their subtlety,
+And let there always be being,
+ so we may see their outcome.
+The two are the same,
+But after they are produced,
+ they have different names.
+They both may be called deep and profound.
+Deeper and more profound,
+The door of all subtleties!
+@end example
+
+In this example, the first hunk contains just the first two lines of
+@file{lao}, the second hunk contains the fourth line of @file{lao}
+opposing the second and third lines of @file{tzu}, and the last hunk
+contains just the last three lines of @file{tzu}.
+
+@node Context
+@section Showing Differences in Their Context
+@cindex context output format
+@cindex @samp{!} output format
+
+Usually, when you are looking at the differences between files, you will
+also want to see the parts of the files near the lines that differ, to
+help you understand exactly what has changed. These nearby parts of the
+files are called the @dfn{context}.
+
+@acronym{GNU} @command{diff} provides two output formats that show context
+around the differing lines: @dfn{context format} and @dfn{unified
+format}. It can optionally show in which function or section of the
+file the differing lines are found.
+
+If you are distributing new versions of files to other people in the
+form of @command{diff} output, you should use one of the output formats
+that show context so that they can apply the diffs even if they have
+made small changes of their own to the files. @command{patch} can apply
+the diffs in this case by searching in the files for the lines of
+context around the differing lines; if those lines are actually a few
+lines away from where the diff says they are, @command{patch} can adjust
+the line numbers accordingly and still apply the diff correctly.
+@xref{Imperfect}, for more information on using @command{patch} to apply
+imperfect diffs.
+
+@menu
+* Context Format:: An output format that shows surrounding lines.
+* Unified Format:: A more compact output format that shows context.
+* Sections:: Showing which sections of the files differences are in.
+* Alternate Names:: Showing alternate file names in context headers.
+@end menu
+
+@node Context Format
+@subsection Context Format
+
+The context output format shows several lines of context around the
+lines that differ. It is the standard format for distributing updates
+to source code.
+
+To select this output format, use the
+@option{--context@r{[}=@var{lines}@r{]}} (@option{-C @var{lines}})
+or @option{-c} option. The
+argument @var{lines} that some of these options take is the number of
+lines of context to show. If you do not specify @var{lines}, it
+defaults to three. For proper operation, @command{patch} typically needs
+at least two lines of context.
+
+@menu
+* Example Context:: Sample output in context format.
+* Less Context:: Another sample with less context.
+* Detailed Context:: A detailed description of the context output format.
+@end menu
+
+@node Example Context
+@subsubsection An Example of Context Format
+
+Here is the output of @samp{diff -c lao tzu} (@pxref{Sample diff Input},
+for the complete contents of the two files). Notice that up to three
+lines that are not different are shown around each line that is
+different; they are the context lines. Also notice that the first two
+hunks have run together, because their contents overlap.
+
+@example
+*** lao 2002-02-21 23:30:39.942229878 -0800
+--- tzu 2002-02-21 23:30:50.442260588 -0800
+***************
+*** 1,7 ****
+- The Way that can be told of is not the eternal Way;
+- The name that can be named is not the eternal name.
+ The Nameless is the origin of Heaven and Earth;
+! The Named is the mother of all things.
+ Therefore let there always be non-being,
+ so we may see their subtlety,
+ And let there always be being,
+--- 1,6 ----
+ The Nameless is the origin of Heaven and Earth;
+! The named is the mother of all things.
+! @-
+ Therefore let there always be non-being,
+ so we may see their subtlety,
+ And let there always be being,
+***************
+*** 9,11 ****
+--- 8,13 ----
+ The two are the same,
+ But after they are produced,
+ they have different names.
++ They both may be called deep and profound.
++ Deeper and more profound,
++ The door of all subtleties!
+@end example
+
+@node Less Context
+@subsubsection An Example of Context Format with Less Context
+
+Here is the output of @samp{diff -C 1 lao tzu} (@pxref{Sample diff
+Input}, for the complete contents of the two files). Notice that at
+most one context line is reported here.
+
+@example
+*** lao 2002-02-21 23:30:39.942229878 -0800
+--- tzu 2002-02-21 23:30:50.442260588 -0800
+***************
+*** 1,5 ****
+- The Way that can be told of is not the eternal Way;
+- The name that can be named is not the eternal name.
+ The Nameless is the origin of Heaven and Earth;
+! The Named is the mother of all things.
+ Therefore let there always be non-being,
+--- 1,4 ----
+ The Nameless is the origin of Heaven and Earth;
+! The named is the mother of all things.
+! @-
+ Therefore let there always be non-being,
+***************
+*** 11 ****
+--- 10,13 ----
+ they have different names.
++ They both may be called deep and profound.
++ Deeper and more profound,
++ The door of all subtleties!
+@end example
+
+@node Detailed Context
+@subsubsection Detailed Description of Context Format
+
+The context output format starts with a two-line header, which looks
+like this:
+
+@example
+*** @var{from-file} @var{from-file-modification-time}
+--- @var{to-file} @var{to-file-modification time}
+@end example
+
+@noindent
+@vindex LC_TIME
+@cindex time stamp format, context diffs
+The time stamp normally looks like @samp{2002-02-21 23:30:39.942229878
+-0800} to indicate the date, time with fractional seconds, and time
+zone in @uref{ftp://ftp.isi.edu/in-notes/rfc2822.txt, Internet RFC
+2822 format}. (The fractional seconds are omitted on hosts that do
+not support fractional time stamps.) However, a traditional time
+stamp like @samp{Thu Feb 21 23:30:39 2002} is used if the
+@env{LC_TIME} locale category is either @samp{C} or @samp{POSIX}.
+
+You can change the header's content with the
+@option{--label=@var{label}} option; see @ref{Alternate Names}.
+
+Next come one or more hunks of differences; each hunk shows one area
+where the files differ. Context format hunks look like this:
+
+@example
+***************
+*** @var{from-file-line-numbers} ****
+ @var{from-file-line}
+ @var{from-file-line}@dots{}
+--- @var{to-file-line-numbers} ----
+ @var{to-file-line}
+ @var{to-file-line}@dots{}
+@end example
+
+If a hunk contains two or more lines, its line numbers look like
+@samp{@var{start},@var{end}}. Otherwise only its end line number
+appears. An empty hunk is considered to end at the line that precedes
+the hunk.
+
+The lines of context around the lines that differ start with two space
+characters. The lines that differ between the two files start with one
+of the following indicator characters, followed by a space character:
+
+@table @samp
+@item !
+A line that is part of a group of one or more lines that changed between
+the two files. There is a corresponding group of lines marked with
+@samp{!} in the part of this hunk for the other file.
+
+@item +
+An ``inserted'' line in the second file that corresponds to nothing in
+the first file.
+
+@item -
+A ``deleted'' line in the first file that corresponds to nothing in the
+second file.
+@end table
+
+If all of the changes in a hunk are insertions, the lines of
+@var{from-file} are omitted. If all of the changes are deletions, the
+lines of @var{to-file} are omitted.
+
+@node Unified Format
+@subsection Unified Format
+@cindex unified output format
+@cindex @samp{+-} output format
+
+The unified output format is a variation on the context format that is
+more compact because it omits redundant context lines. To select this
+output format, use the
+@option{--unified@r{[}=@var{lines}@r{]}} (@option{-U @var{lines}}),
+or @option{-u} option.
+The argument @var{lines} is the number of lines of context to show.
+When it is not given, it defaults to three.
+
+At present, only @acronym{GNU} @command{diff} can produce this format and
+only @acronym{GNU} @command{patch} can automatically apply diffs in this
+format. For proper operation, @command{patch} typically needs at
+least three lines of context.
+
+@menu
+* Example Unified:: Sample output in unified format.
+* Detailed Unified:: A detailed description of unified format.
+@end menu
+
+@node Example Unified
+@subsubsection An Example of Unified Format
+
+Here is the output of the command @samp{diff -u lao tzu}
+(@pxref{Sample diff Input}, for the complete contents of the two files):
+
+@example
+--- lao 2002-02-21 23:30:39.942229878 -0800
++++ tzu 2002-02-21 23:30:50.442260588 -0800
+@@@@ -1,7 +1,6 @@@@
+-The Way that can be told of is not the eternal Way;
+-The name that can be named is not the eternal name.
+ The Nameless is the origin of Heaven and Earth;
+-The Named is the mother of all things.
++The named is the mother of all things.
++
+ Therefore let there always be non-being,
+ so we may see their subtlety,
+ And let there always be being,
+@@@@ -9,3 +8,6 @@@@
+ The two are the same,
+ But after they are produced,
+ they have different names.
++They both may be called deep and profound.
++Deeper and more profound,
++The door of all subtleties!
+@end example
+
+@node Detailed Unified
+@subsubsection Detailed Description of Unified Format
+
+The unified output format starts with a two-line header, which looks
+like this:
+
+@example
+--- @var{from-file} @var{from-file-modification-time}
++++ @var{to-file} @var{to-file-modification-time}
+@end example
+
+@noindent
+@cindex time stamp format, unified diffs
+The time stamp looks like @samp{2002-02-21 23:30:39.942229878 -0800}
+to indicate the date, time with fractional seconds, and time zone.
+The fractional seconds are omitted on hosts that do not support
+fractional time stamps.
+
+You can change the header's content with the
+@option{--label=@var{label}} option. @xref{Alternate Names}.
+
+Next come one or more hunks of differences; each hunk shows one area
+where the files differ. Unified format hunks look like this:
+
+@example
+@@@@ @var{from-file-line-numbers} @var{to-file-line-numbers} @@@@
+ @var{line-from-either-file}
+ @var{line-from-either-file}@dots{}
+@end example
+
+If a hunk contains just one line, only its start line number appears.
+Otherwise its line numbers look like @samp{@var{start},@var{count}}.
+An empty hunk is considered to start at the line that follows the hunk.
+
+If a hunk and its context contain two or more lines, its
+line numbers look like @samp{@var{start},@var{count}}. Otherwise only
+its end line number appears. An empty hunk is considered to end at
+the line that precedes the hunk.
+
+The lines common to both files begin with a space character. The lines
+that actually differ between the two files have one of the following
+indicator characters in the left print column:
+
+@table @samp
+@item +
+A line was added here to the first file.
+
+@item -
+A line was removed here from the first file.
+@end table
+
+@node Sections
+@subsection Showing Which Sections Differences Are in
+@cindex headings
+@cindex section headings
+
+Sometimes you might want to know which part of the files each change
+falls in. If the files are source code, this could mean which
+function was changed. If the files are documents, it could mean which
+chapter or appendix was changed. @acronym{GNU} @command{diff} can
+show this by displaying the nearest section heading line that precedes
+the differing lines. Which lines are ``section headings'' is
+determined by a regular expression.
+
+@menu
+* Specified Headings:: Showing headings that match regular expressions.
+* C Function Headings:: Showing headings of C functions.
+@end menu
+
+@node Specified Headings
+@subsubsection Showing Lines That Match Regular Expressions
+@cindex specified headings
+@cindex regular expression matching headings
+
+To show in which sections differences occur for files that are not
+source code for C or similar languages, use the
+@option{--show-function-line=@var{regexp}} (@option{-F @var{regexp}}) option.
+@command{diff}
+considers lines that match the @command{grep}-style regular expression
+@var{regexp} to be the beginning
+of a section of the file. Here are suggested regular expressions for
+some common languages:
+
+@c Please add to this list, e.g. Fortran, Pascal, Perl, Python.
+@table @samp
+@item ^[[:alpha:]$_]
+C, C++, Prolog
+@item ^(
+Lisp
+@item ^@@node
+Texinfo
+@end table
+
+This option does not automatically select an output format; in order to
+use it, you must select the context format (@pxref{Context Format}) or
+unified format (@pxref{Unified Format}). In other output formats it
+has no effect.
+
+The @option{--show-function-line} (@option{-F}) option finds the nearest
+unchanged line that precedes each hunk of differences and matches the
+given regular expression. Then it adds that line to the end of the
+line of asterisks in the context format, or to the @samp{@@@@} line in
+unified format. If no matching line exists, this option leaves the output for
+that hunk unchanged. If that line is more than 40 characters long, it
+outputs only the first 40 characters. You can specify more than one
+regular expression for such lines; @command{diff} tries to match each line
+against each regular expression, starting with the last one given. This
+means that you can use @option{-p} and @option{-F} together, if you wish.
+
+@node C Function Headings
+@subsubsection Showing C Function Headings
+@cindex C function headings
+@cindex function headings, C
+
+To show in which functions differences occur for C and similar
+languages, you can use the @option{--show-c-function} (@option{-p}) option.
+This option automatically defaults to the context output format
+(@pxref{Context Format}), with the default number of lines of context.
+You can override that number with @option{-C @var{lines}} elsewhere in the
+command line. You can override both the format and the number with
+@option{-U @var{lines}} elsewhere in the command line.
+
+The @option{--show-c-function} (@option{-p}) option is equivalent to
+@option{-F '^[[:alpha:]$_]'} if the unified format is specified, otherwise
+@option{-c -F '^[[:alpha:]$_]'} (@pxref{Specified Headings}). @acronym{GNU}
+@command{diff} provides this option for the sake of convenience.
+
+@node Alternate Names
+@subsection Showing Alternate File Names
+@cindex alternate file names
+@cindex file name alternates
+
+If you are comparing two files that have meaningless or uninformative
+names, you might want @command{diff} to show alternate names in the header
+of the context and unified output formats. To do this, use the
+@option{--label=@var{label}} option. The first time
+you give this option, its argument replaces the name and date of the
+first file in the header; the second time, its argument replaces the
+name and date of the second file. If you give this option more than
+twice, @command{diff} reports an error. The @option{--label} option does not
+affect the file names in the @command{pr} header when the @option{-l} or
+@option{--paginate} option is used (@pxref{Pagination}).
+
+Here are the first two lines of the output from @samp{diff -C 2
+--label=original --label=modified lao tzu}:
+
+@example
+*** original
+--- modified
+@end example
+
+@node Side by Side
+@section Showing Differences Side by Side
+@cindex side by side
+@cindex two-column output
+@cindex columnar output
+
+@command{diff} can produce a side by side difference listing of two files.
+The files are listed in two columns with a gutter between them. The
+gutter contains one of the following markers:
+
+@table @asis
+@item white space
+The corresponding lines are in common. That is, either the lines are
+identical, or the difference is ignored because of one of the
+@option{--ignore} options (@pxref{White Space}).
+
+@item @samp{|}
+The corresponding lines differ, and they are either both complete
+or both incomplete.
+
+@item @samp{<}
+The files differ and only the first file contains the line.
+
+@item @samp{>}
+The files differ and only the second file contains the line.
+
+@item @samp{(}
+Only the first file contains the line, but the difference is ignored.
+
+@item @samp{)}
+Only the second file contains the line, but the difference is ignored.
+
+@item @samp{\}
+The corresponding lines differ, and only the first line is incomplete.
+
+@item @samp{/}
+The corresponding lines differ, and only the second line is incomplete.
+@end table
+
+Normally, an output line is incomplete if and only if the lines that it
+contains are incomplete. @xref{Incomplete Lines}. However, when an
+output line represents two differing lines, one might be incomplete
+while the other is not. In this case, the output line is complete,
+but its the gutter is marked @samp{\} if the first line is incomplete,
+@samp{/} if the second line is.
+
+Side by side format is sometimes easiest to read, but it has limitations.
+It generates much wider output than usual, and truncates lines that are
+too long to fit. Also, it relies on lining up output more heavily than
+usual, so its output looks particularly bad if you use varying
+width fonts, nonstandard tab stops, or nonprinting characters.
+
+You can use the @command{sdiff} command to interactively merge side by side
+differences. @xref{Interactive Merging}, for more information on merging files.
+
+@menu
+* Side by Side Format:: Controlling side by side output format.
+* Example Side by Side:: Sample side by side output.
+@end menu
+
+@node Side by Side Format
+@subsection Controlling Side by Side Format
+@cindex side by side format
+
+The @option{--side-by-side} (@option{-y}) option selects side by side
+format. Because side by side output lines contain two input lines, the
+output is wider than usual: normally 130 print columns, which can fit
+onto a traditional printer line. You can set the width of the output
+with the @option{--width=@var{columns}} (@option{-W @var{columns}})
+option. The output is split into two halves of equal width, separated by a
+small gutter to mark differences; the right half is aligned to a tab
+stop so that tabs line up. Input lines that are too long to fit in half
+of an output line are truncated for output.
+
+The @option{--left-column} option prints only the left column of two
+common lines. The @option{--suppress-common-lines} option suppresses
+common lines entirely.
+
+@node Example Side by Side
+@subsection An Example of Side by Side Format
+
+Here is the output of the command @samp{diff -y -W 72 lao tzu}
+(@pxref{Sample diff Input}, for the complete contents of the two files).
+
+@example
+The Way that can be told of is n <
+The name that can be named is no <
+The Nameless is the origin of He The Nameless is the origin of He
+The Named is the mother of all t | The named is the mother of all t
+ >
+Therefore let there always be no Therefore let there always be no
+ so we may see their subtlety, so we may see their subtlety,
+And let there always be being, And let there always be being,
+ so we may see their outcome. so we may see their outcome.
+The two are the same, The two are the same,
+But after they are produced, But after they are produced,
+ they have different names. they have different names.
+ > They both may be called deep and
+ > Deeper and more profound,
+ > The door of all subtleties!
+@end example
+
+@node Normal
+@section Showing Differences Without Context
+@cindex normal output format
+@cindex @samp{<} output format
+
+The ``normal'' @command{diff} output format shows each hunk of differences
+without any surrounding context. Sometimes such output is the clearest
+way to see how lines have changed, without the clutter of nearby
+unchanged lines (although you can get similar results with the context
+or unified formats by using 0 lines of context). However, this format
+is no longer widely used for sending out patches; for that purpose, the
+context format (@pxref{Context Format}) and the unified format
+(@pxref{Unified Format}) are superior. Normal format is the default for
+compatibility with older versions of @command{diff} and the @acronym{POSIX}
+standard. Use the @option{--normal} option to select this output
+format explicitly.
+
+@menu
+* Example Normal:: Sample output in the normal format.
+* Detailed Normal:: A detailed description of normal output format.
+@end menu
+
+@node Example Normal
+@subsection An Example of Normal Format
+
+Here is the output of the command @samp{diff lao tzu}
+(@pxref{Sample diff Input}, for the complete contents of the two files).
+Notice that it shows only the lines that are different between the two
+files.
+
+@example
+1,2d0
+< The Way that can be told of is not the eternal Way;
+< The name that can be named is not the eternal name.
+4c2,3
+< The Named is the mother of all things.
+---
+> The named is the mother of all things.
+> @-
+11a11,13
+> They both may be called deep and profound.
+> Deeper and more profound,
+> The door of all subtleties!
+@end example
+
+@node Detailed Normal
+@subsection Detailed Description of Normal Format
+
+The normal output format consists of one or more hunks of differences;
+each hunk shows one area where the files differ. Normal format hunks
+look like this:
+
+@example
+@var{change-command}
+< @var{from-file-line}
+< @var{from-file-line}@dots{}
+---
+> @var{to-file-line}
+> @var{to-file-line}@dots{}
+@end example
+
+There are three types of change commands. Each consists of a line
+number or comma-separated range of lines in the first file, a single
+character indicating the kind of change to make, and a line number or
+comma-separated range of lines in the second file. All line numbers are
+the original line numbers in each file. The types of change commands
+are:
+
+@table @samp
+@item @var{l}a@var{r}
+Add the lines in range @var{r} of the second file after line @var{l} of
+the first file. For example, @samp{8a12,15} means append lines 12--15
+of file 2 after line 8 of file 1; or, if changing file 2 into file 1,
+delete lines 12--15 of file 2.
+
+@item @var{f}c@var{t}
+Replace the lines in range @var{f} of the first file with lines in range
+@var{t} of the second file. This is like a combined add and delete, but
+more compact. For example, @samp{5,7c8,10} means change lines 5--7 of
+file 1 to read as lines 8--10 of file 2; or, if changing file 2 into
+file 1, change lines 8--10 of file 2 to read as lines 5--7 of file 1.
+
+@item @var{r}d@var{l}
+Delete the lines in range @var{r} from the first file; line @var{l} is where
+they would have appeared in the second file had they not been deleted.
+For example, @samp{5,7d3} means delete lines 5--7 of file 1; or, if
+changing file 2 into file 1, append lines 5--7 of file 1 after line 3 of
+file 2.
+@end table
+
+@node Scripts
+@section Making Edit Scripts
+@cindex script output formats
+
+Several output modes produce command scripts for editing @var{from-file}
+to produce @var{to-file}.
+
+@menu
+* ed Scripts:: Using @command{diff} to produce commands for @command{ed}.
+* Forward ed:: Making forward @command{ed} scripts.
+* RCS:: A special @command{diff} output format used by @acronym{RCS}.
+@end menu
+
+@node ed Scripts
+@subsection @command{ed} Scripts
+@cindex @command{ed} script output format
+
+@command{diff} can produce commands that direct the @command{ed} text editor
+to change the first file into the second file. Long ago, this was the
+only output mode that was suitable for editing one file into another
+automatically; today, with @command{patch}, it is almost obsolete. Use the
+@option{--ed} (@option{-e}) option to select this output format.
+
+Like the normal format (@pxref{Normal}), this output format does not
+show any context; unlike the normal format, it does not include the
+information necessary to apply the diff in reverse (to produce the first
+file if all you have is the second file and the diff).
+
+If the file @file{d} contains the output of @samp{diff -e old new}, then
+the command @samp{(cat d && echo w) | ed - old} edits @file{old} to make
+it a copy of @file{new}. More generally, if @file{d1}, @file{d2},
+@dots{}, @file{dN} contain the outputs of @samp{diff -e old new1},
+@samp{diff -e new1 new2}, @dots{}, @samp{diff -e newN-1 newN},
+respectively, then the command @samp{(cat d1 d2 @dots{} dN && echo w) |
+ed - old} edits @file{old} to make it a copy of @file{newN}.
+
+@menu
+* Example ed:: A sample @command{ed} script.
+* Detailed ed:: A detailed description of @command{ed} format.
+@end menu
+
+@node Example ed
+@subsubsection Example @command{ed} Script
+
+Here is the output of @samp{diff -e lao tzu} (@pxref{Sample
+diff Input}, for the complete contents of the two files):
+
+@example
+11a
+They both may be called deep and profound.
+Deeper and more profound,
+The door of all subtleties!
+.
+4c
+The named is the mother of all things.
+
+.
+1,2d
+@end example
+
+@node Detailed ed
+@subsubsection Detailed Description of @command{ed} Format
+
+The @command{ed} output format consists of one or more hunks of
+differences. The changes closest to the ends of the files come first so
+that commands that change the number of lines do not affect how
+@command{ed} interprets line numbers in succeeding commands. @command{ed}
+format hunks look like this:
+
+@example
+@var{change-command}
+@var{to-file-line}
+@var{to-file-line}@dots{}
+.
+@end example
+
+Because @command{ed} uses a single period on a line to indicate the
+end of input, @acronym{GNU} @command{diff} protects lines of changes
+that contain a single period on a line by writing two periods instead,
+then writing a subsequent @command{ed} command to change the two
+periods into one. The @command{ed} format cannot represent an
+incomplete line, so if the second file ends in a changed incomplete
+line, @command{diff} reports an error and then pretends that a newline
+was appended.
+
+There are three types of change commands. Each consists of a line
+number or comma-separated range of lines in the first file and a single
+character indicating the kind of change to make. All line numbers are
+the original line numbers in the file. The types of change commands
+are:
+
+@table @samp
+@item @var{l}a
+Add text from the second file after line @var{l} in the first file. For
+example, @samp{8a} means to add the following lines after line 8 of file
+1.
+
+@item @var{r}c
+Replace the lines in range @var{r} in the first file with the following
+lines. Like a combined add and delete, but more compact. For example,
+@samp{5,7c} means change lines 5--7 of file 1 to read as the text file
+2.
+
+@item @var{r}d
+Delete the lines in range @var{r} from the first file. For example,
+@samp{5,7d} means delete lines 5--7 of file 1.
+@end table
+
+@node Forward ed
+@subsection Forward @command{ed} Scripts
+@cindex forward @command{ed} script output format
+
+@command{diff} can produce output that is like an @command{ed} script, but
+with hunks in forward (front to back) order. The format of the commands
+is also changed slightly: command characters precede the lines they
+modify, spaces separate line numbers in ranges, and no attempt is made
+to disambiguate hunk lines consisting of a single period. Like
+@command{ed} format, forward @command{ed} format cannot represent incomplete
+lines.
+
+Forward @command{ed} format is not very useful, because neither @command{ed}
+nor @command{patch} can apply diffs in this format. It exists mainly for
+compatibility with older versions of @command{diff}. Use the @option{-f} or
+@option{--forward-ed} option to select it.
+
+@node RCS
+@subsection @acronym{RCS} Scripts
+@cindex @acronym{RCS} script output format
+
+The @acronym{RCS} output format is designed specifically for use by
+the Revision Control System, which is a set of free programs used for
+organizing different versions and systems of files. Use the
+@option{--rcs} (@option{-n}) option to select this output format. It
+is like the forward @command{ed} format (@pxref{Forward ed}), but it
+can represent arbitrary changes to the contents of a file because it
+avoids the forward @command{ed} format's problems with lines
+consisting of a single period and with incomplete lines. Instead of
+ending text sections with a line consisting of a single period, each
+command specifies the number of lines it affects; a combination of the
+@samp{a} and @samp{d} commands are used instead of @samp{c}. Also, if
+the second file ends in a changed incomplete line, then the output
+also ends in an incomplete line.
+
+Here is the output of @samp{diff -n lao tzu} (@pxref{Sample
+diff Input}, for the complete contents of the two files):
+
+@example
+d1 2
+d4 1
+a4 2
+The named is the mother of all things.
+
+a11 3
+They both may be called deep and profound.
+Deeper and more profound,
+The door of all subtleties!
+@end example
+
+@node If-then-else
+@section Merging Files with If-then-else
+@cindex merged output format
+@cindex if-then-else output format
+@cindex C if-then-else output format
+@cindex @command{ifdef} output format
+
+You can use @command{diff} to merge two files of C source code. The output
+of @command{diff} in this format contains all the lines of both files.
+Lines common to both files are output just once; the differing parts are
+separated by the C preprocessor directives @code{#ifdef @var{name}} or
+@code{#ifndef @var{name}}, @code{#else}, and @code{#endif}. When
+compiling the output, you select which version to use by either defining
+or leaving undefined the macro @var{name}.
+
+To merge two files, use @command{diff} with the @option{-D @var{name}} or
+@option{--ifdef=@var{name}} option. The argument @var{name} is the C
+preprocessor identifier to use in the @code{#ifdef} and @code{#ifndef}
+directives.
+
+For example, if you change an instance of @code{wait (&s)} to
+@code{waitpid (-1, &s, 0)} and then merge the old and new files with
+the @option{--ifdef=HAVE_WAITPID} option, then the affected part of your code
+might look like this:
+
+@example
+ do @{
+#ifndef HAVE_WAITPID
+ if ((w = wait (&s)) < 0 && errno != EINTR)
+#else /* HAVE_WAITPID */
+ if ((w = waitpid (-1, &s, 0)) < 0 && errno != EINTR)
+#endif /* HAVE_WAITPID */
+ return w;
+ @} while (w != child);
+@end example
+
+You can specify formats for languages other than C by using line group
+formats and line formats, as described in the next sections.
+
+@menu
+* Line Group Formats:: Formats for general if-then-else line groups.
+* Line Formats:: Formats for each line in a line group.
+* Example If-then-else:: Sample if-then-else format output.
+* Detailed If-then-else:: A detailed description of if-then-else format.
+@end menu
+
+@node Line Group Formats
+@subsection Line Group Formats
+@cindex line group formats
+@cindex formats for if-then-else line groups
+
+Line group formats let you specify formats suitable for many
+applications that allow if-then-else input, including programming
+languages and text formatting languages. A line group format specifies
+the output format for a contiguous group of similar lines.
+
+For example, the following command compares the TeX files @file{old}
+and @file{new}, and outputs a merged file in which old regions are
+surrounded by @samp{\begin@{em@}}-@samp{\end@{em@}} lines, and new
+regions are surrounded by @samp{\begin@{bf@}}-@samp{\end@{bf@}} lines.
+
+@example
+diff \
+ --old-group-format='\begin@{em@}
+%<\end@{em@}
+' \
+ --new-group-format='\begin@{bf@}
+%>\end@{bf@}
+' \
+ old new
+@end example
+
+The following command is equivalent to the above example, but it is a
+little more verbose, because it spells out the default line group formats.
+
+@example
+diff \
+ --old-group-format='\begin@{em@}
+%<\end@{em@}
+' \
+ --new-group-format='\begin@{bf@}
+%>\end@{bf@}
+' \
+ --unchanged-group-format='%=' \
+ --changed-group-format='\begin@{em@}
+%<\end@{em@}
+\begin@{bf@}
+%>\end@{bf@}
+' \
+ old new
+@end example
+
+Here is a more advanced example, which outputs a diff listing with
+headers containing line numbers in a ``plain English'' style.
+
+@example
+diff \
+ --unchanged-group-format='' \
+ --old-group-format='-------- %dn line%(n=1?:s) deleted at %df:
+%<' \
+ --new-group-format='-------- %dN line%(N=1?:s) added after %de:
+%>' \
+ --changed-group-format='-------- %dn line%(n=1?:s) changed at %df:
+%<-------- to:
+%>' \
+ old new
+@end example
+
+To specify a line group format, use @command{diff} with one of the options
+listed below. You can specify up to four line group formats, one for
+each kind of line group. You should quote @var{format}, because it
+typically contains shell metacharacters.
+
+@table @option
+@item --old-group-format=@var{format}
+These line groups are hunks containing only lines from the first file.
+The default old group format is the same as the changed group format if
+it is specified; otherwise it is a format that outputs the line group as-is.
+
+@item --new-group-format=@var{format}
+These line groups are hunks containing only lines from the second
+file. The default new group format is same as the changed group
+format if it is specified; otherwise it is a format that outputs the
+line group as-is.
+
+@item --changed-group-format=@var{format}
+These line groups are hunks containing lines from both files. The
+default changed group format is the concatenation of the old and new
+group formats.
+
+@item --unchanged-group-format=@var{format}
+These line groups contain lines common to both files. The default
+unchanged group format is a format that outputs the line group as-is.
+@end table
+
+In a line group format, ordinary characters represent themselves;
+conversion specifications start with @samp{%} and have one of the
+following forms.
+
+@table @samp
+@item %<
+stands for the lines from the first file, including the trailing newline.
+Each line is formatted according to the old line format (@pxref{Line Formats}).
+
+@item %>
+stands for the lines from the second file, including the trailing newline.
+Each line is formatted according to the new line format.
+
+@item %=
+stands for the lines common to both files, including the trailing newline.
+Each line is formatted according to the unchanged line format.
+
+@item %%
+stands for @samp{%}.
+
+@item %c'@var{C}'
+where @var{C} is a single character, stands for @var{C}.
+@var{C} may not be a backslash or an apostrophe.
+For example, @samp{%c':'} stands for a colon, even inside
+the then-part of an if-then-else format, which a colon would
+normally terminate.
+
+@item %c'\@var{O}'
+where @var{O} is a string of 1, 2, or 3 octal digits,
+stands for the character with octal code @var{O}.
+For example, @samp{%c'\0'} stands for a null character.
+
+@item @var{F}@var{n}
+where @var{F} is a @code{printf} conversion specification and @var{n} is one
+of the following letters, stands for @var{n}'s value formatted with @var{F}.
+
+@table @samp
+@item e
+The line number of the line just before the group in the old file.
+
+@item f
+The line number of the first line in the group in the old file;
+equals @var{e} + 1.
+
+@item l
+The line number of the last line in the group in the old file.
+
+@item m
+The line number of the line just after the group in the old file;
+equals @var{l} + 1.
+
+@item n
+The number of lines in the group in the old file; equals @var{l} - @var{f} + 1.
+
+@item E, F, L, M, N
+Likewise, for lines in the new file.
+
+@end table
+
+@vindex LC_NUMERIC
+The @code{printf} conversion specification can be @samp{%d},
+@samp{%o}, @samp{%x}, or @samp{%X}, specifying decimal, octal,
+lower case hexadecimal, or upper case hexadecimal output
+respectively. After the @samp{%} the following options can appear in
+sequence: a series of zero or more flags; an integer
+specifying the minimum field width; and a period followed by an
+optional integer specifying the minimum number of digits.
+The flags are @samp{-} for left-justification, @samp{'} for separating
+the digit into groups as specified by the @env{LC_NUMERIC} locale category,
+and @samp{0} for padding with zeros instead of spaces.
+For example, @samp{%5dN} prints the number of new lines in the group
+in a field of width 5 characters, using the @code{printf} format @code{"%5d"}.
+
+@item (@var{A}=@var{B}?@var{T}:@var{E})
+If @var{A} equals @var{B} then @var{T} else @var{E}.
+@var{A} and @var{B} are each either a decimal constant
+or a single letter interpreted as above.
+This format spec is equivalent to @var{T} if
+@var{A}'s value equals @var{B}'s; otherwise it is equivalent to @var{E}.
+
+For example, @samp{%(N=0?no:%dN) line%(N=1?:s)} is equivalent to
+@samp{no lines} if @var{N} (the number of lines in the group in the
+new file) is 0, to @samp{1 line} if @var{N} is 1, and to @samp{%dN lines}
+otherwise.
+@end table
+
+@node Line Formats
+@subsection Line Formats
+@cindex line formats
+
+Line formats control how each line taken from an input file is
+output as part of a line group in if-then-else format.
+
+For example, the following command outputs text with a one-character
+change indicator to the left of the text. The first character of output
+is @samp{-} for deleted lines, @samp{|} for added lines, and a space for
+unchanged lines. The formats contain newline characters where newlines
+are desired on output.
+
+@example
+diff \
+ --old-line-format='-%l
+' \
+ --new-line-format='|%l
+' \
+ --unchanged-line-format=' %l
+' \
+ old new
+@end example
+
+To specify a line format, use one of the following options. You should
+quote @var{format}, since it often contains shell metacharacters.
+
+@table @option
+@item --old-line-format=@var{format}
+formats lines just from the first file.
+
+@item --new-line-format=@var{format}
+formats lines just from the second file.
+
+@item --unchanged-line-format=@var{format}
+formats lines common to both files.
+
+@item --line-format=@var{format}
+formats all lines; in effect, it sets all three above options simultaneously.
+@end table
+
+In a line format, ordinary characters represent themselves;
+conversion specifications start with @samp{%} and have one of the
+following forms.
+
+@table @samp
+@item %l
+stands for the contents of the line, not counting its trailing
+newline (if any). This format ignores whether the line is incomplete;
+@xref{Incomplete Lines}.
+
+@item %L
+stands for the contents of the line, including its trailing newline
+(if any). If a line is incomplete, this format preserves its
+incompleteness.
+
+@item %%
+stands for @samp{%}.
+
+@item %c'@var{C}'
+where @var{C} is a single character, stands for @var{C}.
+@var{C} may not be a backslash or an apostrophe.
+For example, @samp{%c':'} stands for a colon.
+
+@item %c'\@var{O}'
+where @var{O} is a string of 1, 2, or 3 octal digits,
+stands for the character with octal code @var{O}.
+For example, @samp{%c'\0'} stands for a null character.
+
+@item @var{F}n
+where @var{F} is a @code{printf} conversion specification,
+stands for the line number formatted with @var{F}.
+For example, @samp{%.5dn} prints the line number using the
+@code{printf} format @code{"%.5d"}. @xref{Line Group Formats}, for
+more about printf conversion specifications.
+
+@end table
+
+The default line format is @samp{%l} followed by a newline character.
+
+If the input contains tab characters and it is important that they line
+up on output, you should ensure that @samp{%l} or @samp{%L} in a line
+format is just after a tab stop (e.g.@: by preceding @samp{%l} or
+@samp{%L} with a tab character), or you should use the @option{-t} or
+@option{--expand-tabs} option.
+
+Taken together, the line and line group formats let you specify many
+different formats. For example, the following command uses a format
+similar to normal @command{diff} format. You can tailor this command
+to get fine control over @command{diff} output.
+
+@example
+diff \
+ --old-line-format='< %l
+' \
+ --new-line-format='> %l
+' \
+ --old-group-format='%df%(f=l?:,%dl)d%dE
+%<' \
+ --new-group-format='%dea%dF%(F=L?:,%dL)
+%>' \
+ --changed-group-format='%df%(f=l?:,%dl)c%dF%(F=L?:,%dL)
+%<---
+%>' \
+ --unchanged-group-format='' \
+ old new
+@end example
+
+@node Example If-then-else
+@subsection An Example of If-then-else Format
+
+Here is the output of @samp{diff -DTWO lao tzu} (@pxref{Sample
+diff Input}, for the complete contents of the two files):
+
+@example
+#ifndef TWO
+The Way that can be told of is not the eternal Way;
+The name that can be named is not the eternal name.
+#endif /* ! TWO */
+The Nameless is the origin of Heaven and Earth;
+#ifndef TWO
+The Named is the mother of all things.
+#else /* TWO */
+The named is the mother of all things.
+
+#endif /* TWO */
+Therefore let there always be non-being,
+ so we may see their subtlety,
+And let there always be being,
+ so we may see their outcome.
+The two are the same,
+But after they are produced,
+ they have different names.
+#ifdef TWO
+They both may be called deep and profound.
+Deeper and more profound,
+The door of all subtleties!
+#endif /* TWO */
+@end example
+
+@node Detailed If-then-else
+@subsection Detailed Description of If-then-else Format
+
+For lines common to both files, @command{diff} uses the unchanged line
+group format. For each hunk of differences in the merged output
+format, if the hunk contains only lines from the first file,
+@command{diff} uses the old line group format; if the hunk contains only
+lines from the second file, @command{diff} uses the new group format;
+otherwise, @command{diff} uses the changed group format.
+
+The old, new, and unchanged line formats specify the output format of
+lines from the first file, lines from the second file, and lines common
+to both files, respectively.
+
+The option @option{--ifdef=@var{name}} is equivalent to
+the following sequence of options using shell syntax:
+
+@example
+--old-group-format='#ifndef @var{name}
+%<#endif /* ! @var{name} */
+' \
+--new-group-format='#ifdef @var{name}
+%>#endif /* @var{name} */
+' \
+--unchanged-group-format='%=' \
+--changed-group-format='#ifndef @var{name}
+%<#else /* @var{name} */
+%>#endif /* @var{name} */
+'
+@end example
+
+You should carefully check the @command{diff} output for proper nesting.
+For example, when using the @option{-D @var{name}} or
+@option{--ifdef=@var{name}} option, you should check that if the
+differing lines contain any of the C preprocessor directives
+@samp{#ifdef}, @samp{#ifndef}, @samp{#else}, @samp{#elif}, or
+@samp{#endif}, they are nested properly and match. If they don't, you
+must make corrections manually. It is a good idea to carefully check
+the resulting code anyway to make sure that it really does what you
+want it to; depending on how the input files were produced, the output
+might contain duplicate or otherwise incorrect code.
+
+The @command{patch} @option{-D @var{name}} option behaves like
+the @command{diff} @option{-D @var{name}} option, except it operates on
+a file and a diff to produce a merged file. @xref{patch Options}.
+
+@node Incomplete Lines
+@chapter Incomplete Lines
+@cindex incomplete lines
+@cindex full lines
+@cindex newline treatment by @command{diff}
+
+When an input file ends in a non-newline character, its last line is
+called an @dfn{incomplete line} because its last character is not a
+newline. All other lines are called @dfn{full lines} and end in a
+newline character. Incomplete lines do not match full lines unless
+differences in white space are ignored (@pxref{White Space}).
+
+An incomplete line is normally distinguished on output from a full
+line by a following line that starts with @samp{\}. However, the
+@acronym{RCS} format (@pxref{RCS}) outputs the incomplete line as-is,
+without any trailing newline or following line. The side by side
+format normally represents incomplete lines as-is, but in some cases
+uses a @samp{\} or @samp{/} gutter marker. @xref{Side by Side}. The
+if-then-else line format preserves a line's incompleteness with
+@samp{%L}, and discards the newline with @samp{%l}. @xref{Line Formats}.
+Finally, with the @command{ed} and forward @command{ed}
+output formats (@pxref{Output Formats}) @command{diff} cannot
+represent an incomplete line, so it pretends there was a newline and
+reports an error.
+
+For example, suppose @file{F} and @file{G} are one-byte files that
+contain just @samp{f} and @samp{g}, respectively. Then @samp{diff F G}
+outputs
+
+@example
+1c1
+< f
+\ No newline at end of file
+---
+> g
+\ No newline at end of file
+@end example
+
+@noindent
+(The exact message may differ in non-English locales.)
+@samp{diff -n F G} outputs the following without a trailing newline:
+
+@example
+d1 1
+a1 1
+g
+@end example
+
+@noindent
+@samp{diff -e F G} reports two errors and outputs the following:
+
+@example
+1c
+g
+.
+@end example
+
+@node Comparing Directories
+@chapter Comparing Directories
+
+@vindex LC_COLLATE
+You can use @command{diff} to compare some or all of the files in two
+directory trees. When both file name arguments to @command{diff} are
+directories, it compares each file that is contained in both
+directories, examining file names in alphabetical order as specified by
+the @env{LC_COLLATE} locale category. Normally
+@command{diff} is silent about pairs of files that contain no differences,
+but if you use the @option{--report-identical-files} (@option{-s}) option,
+it reports pairs of identical files. Normally @command{diff} reports
+subdirectories common to both directories without comparing
+subdirectories' files, but if you use the @option{-r} or
+@option{--recursive} option, it compares every corresponding pair of files
+in the directory trees, as many levels deep as they go.
+
+If only one file exists, @command{diff} normally does not show its
+contents; it merely reports that one file exists but the other does
+not. You can make @command{diff} act as though the missing file is
+empty, so that it outputs the entire contents of the file that
+actually exists. (It is output as either an insertion or a
+deletion, depending on whether the missing file is in the first or the
+second position.) To do this, use the @option{--new-file}
+(@option{-N}) option. This option affects command-line arguments as
+well as files found via directory traversal; for example, @samp{diff
+-N a b} treats @file{a} as empty if @file{a} does not exist but
+@file{b} does, and similarly @samp{diff -N - b} treats standard input
+as empty if it is closed but @file{b} exists.
+
+If the older directory contains large files that are not in
+the newer directory, you can make the patch smaller by using the
+@option{--unidirectional-new-file} option instead of @option{-N}.
+This option is like @option{-N} except that it inserts the contents only
+of files that appear in the second directory but not the first (that is,
+files that were added). At the top of the patch, write instructions for
+the user applying the patch to remove the files that were deleted before
+applying the patch. @xref{Making Patches}, for more discussion of
+making patches for distribution.
+
+To ignore some files while comparing directories, use the
+@option{--exclude=@var{pattern}} (@option{-x @var{pattern}}) option.
+This option
+ignores any files or subdirectories whose base names match the shell
+pattern @var{pattern}. Unlike in the shell, a period at the start of
+the base of a file name matches a wildcard at the start of a pattern.
+You should enclose @var{pattern} in quotes so that the shell does not
+expand it. For example, the option @option{-x '*.[ao]'} ignores any file
+whose name ends with @samp{.a} or @samp{.o}.
+
+This option accumulates if you specify it more than once. For example,
+using the options @option{-x 'RCS' -x '*,v'} ignores any file or
+subdirectory whose base name is @samp{RCS} or ends with @samp{,v}.
+
+If you need to give this option many times, you can instead put the
+patterns in a file, one pattern per line, and use the
+@option{--exclude-from=@var{file}} (@option{-X @var{file}}) option.
+Trailing white space and empty lines are ignored in the pattern file.
+
+If you have been comparing two directories and stopped partway through,
+later you might want to continue where you left off. You can do this by
+using the @option{--starting-file=@var{file}} (@option{-S @var{file}})
+option. This compares only the file @var{file} and all alphabetically
+later files in the topmost directory level.
+
+If two directories differ only in that file names are lower case in
+one directory and upper case in the upper, @command{diff} normally
+reports many differences because it compares file names in a
+case sensitive way. With the @option{--ignore-file-name-case} option,
+@command{diff} ignores case differences in file names, so that for example
+the contents of the file @file{Tao} in one directory are compared to
+the contents of the file @file{TAO} in the other. The
+@option{--no-ignore-file-name-case} option cancels the effect of the
+@option{--ignore-file-name-case} option, reverting to the default
+behavior.
+
+If an @option{--exclude=@var{pattern}} (@option{-x @var{pattern}}) option,
+or an @option{--exclude-from=@var{file}} (@option{-X @var{file}}) option,
+is specified while the @option{--ignore-file-name-case} option is in
+effect, case is ignored when excluding file names matching the
+specified patterns.
+
+To tell @command{diff} not to follow a symbolic link, use the
+@c later: @option{--no-dereference} (@option{-P}).
+@option{--no-dereference} option.
+
+@node Adjusting Output
+@chapter Making @command{diff} Output Prettier
+
+@command{diff} provides several ways to adjust the appearance of its output.
+These adjustments can be applied to any output format.
+
+@menu
+* Tabs:: Preserving the alignment of tab stops.
+* Trailing Blanks:: Suppressing blanks before empty output lines.
+* Pagination:: Page numbering and time-stamping @command{diff} output.
+@end menu
+
+@node Tabs
+@section Preserving Tab Stop Alignment
+@cindex tab stop alignment
+@cindex aligning tab stops
+
+The lines of text in some of the @command{diff} output formats are
+preceded by one or two characters that indicate whether the text is
+inserted, deleted, or changed. The addition of those characters can
+cause tabs to move to the next tab stop, throwing off the alignment of
+columns in the line. @acronym{GNU} @command{diff} provides two ways
+to make tab-aligned columns line up correctly.
+
+The first way is to have @command{diff} convert all tabs into the correct
+number of spaces before outputting them; select this method with the
+@option{--expand-tabs} (@option{-t}) option. To use this form of output with
+@command{patch}, you must give @command{patch} the @option{-l} or
+@option{--ignore-white-space} option (@pxref{Changed White Space}, for more
+information). @command{diff} normally assumes that tab stops are set
+every 8 print columns, but this can be altered by the
+@option{--tabsize=@var{columns}} option.
+
+The other method for making tabs line up correctly is to add a tab
+character instead of a space after the indicator character at the
+beginning of the line. This ensures that all following tab characters
+are in the same position relative to tab stops that they were in the
+original files, so that the output is aligned correctly. Its
+disadvantage is that it can make long lines too long to fit on one line
+of the screen or the paper. It also does not work with the unified
+output format, which does not have a space character after the change
+type indicator character. Select this method with the @option{-T} or
+@option{--initial-tab} option.
+
+@node Trailing Blanks
+@section Omitting trailing blanks
+@cindex trailing blanks
+When outputting lines in normal or context format, or outputting an
+unchanged line in unified format, @command{diff} normally outputs a
+blank just before each line. If the line is empty, the output of
+@command{diff} therefore contains trailing blanks even though the
+input does not contain them. For example, when outputting an
+unchanged empty line in context format, @command{diff} normally
+outputs a line with two leading spaces.
+
+Some text editors and email agents routinely delete trailing blanks,
+so it can be a problem to deal with diff output files that contain
+them. You can avoid this problem with the
+@option{--suppress-blank-empty} option. It causes @command{diff} to
+omit trailing blanks at the end of output lines in normal, context,
+and unified format, unless the trailing blanks were already present in
+the input. This changes the output format slightly, so that output
+lines are guaranteed to never end in a blank unless an input line ends
+in a blank. This format is less likely to be munged by text editors
+or by transmission via email. It is accepted by @acronym{GNU}
+@command{patch} as well.
+
+@node Pagination
+@section Paginating @command{diff} Output
+@cindex paginating @command{diff} output
+
+It can be convenient to have long output page-numbered and time-stamped.
+The @option{--paginate} (@option{-l}) option does this by sending the
+@command{diff} output through the @command{pr} program. Here is what the page
+header might look like for @samp{diff -lc lao tzu}:
+
+@example
+2002-02-22 14:20 diff -lc lao tzu Page 1
+@end example
+
+@node diff Performance
+@chapter @command{diff} Performance Tradeoffs
+@cindex performance of @command{diff}
+
+@acronym{GNU} @command{diff} runs quite efficiently; however, in some
+circumstances you can cause it to run faster or produce a more compact
+set of changes.
+
+One way to improve @command{diff} performance is to use hard or
+symbolic links to files instead of copies. This improves performance
+because @command{diff} normally does not need to read two hard or
+symbolic links to the same file, since their contents must be
+identical. For example, suppose you copy a large directory hierarchy,
+make a few changes to the copy, and then often use @samp{diff -r} to
+compare the original to the copy. If the original files are
+read-only, you can greatly improve performance by creating the copy
+using hard or symbolic links (e.g., with @acronym{GNU} @samp{cp -lR} or
+@samp{cp -sR}). Before editing a file in the copy for the first time,
+you should break the link and replace it with a regular copy.
+
+You can also affect the performance of @acronym{GNU} @command{diff} by
+giving it options that change the way it compares files.
+Performance has more than one dimension. These options improve one
+aspect of performance at the cost of another, or they improve
+performance in some cases while hurting it in others.
+
+The way that @acronym{GNU} @command{diff} determines which lines have
+changed always comes up with a near-minimal set of differences.
+Usually it is good enough for practical purposes. If the
+@command{diff} output is large, you might want @command{diff} to use a
+modified algorithm that sometimes produces a smaller set of
+differences. The @option{--minimal} (@option{-d}) option does this;
+however, it can also cause @command{diff} to run more slowly than
+usual, so it is not the default behavior.
+
+When the files you are comparing are large and have small groups of
+changes scattered throughout them, you can use the
+@option{--speed-large-files} option to make a different modification to
+the algorithm that @command{diff} uses. If the input files have a constant
+small density of changes, this option speeds up the comparisons without
+changing the output. If not, @command{diff} might produce a larger set of
+differences; however, the output will still be correct.
+
+Normally @command{diff} discards the prefix and suffix that is common to
+both files before it attempts to find a minimal set of differences.
+This makes @command{diff} run faster, but occasionally it may produce
+non-minimal output. The @option{--horizon-lines=@var{lines}} option
+prevents @command{diff} from discarding the last @var{lines} lines of the
+prefix and the first @var{lines} lines of the suffix. This gives
+@command{diff} further opportunities to find a minimal output.
+
+Suppose a run of changed lines includes a sequence of lines at one end
+and there is an identical sequence of lines just outside the other end.
+The @command{diff} command is free to choose which identical sequence is
+included in the hunk. In this case, @command{diff} normally shifts the
+hunk's boundaries when this merges adjacent hunks, or shifts a hunk's
+lines towards the end of the file. Merging hunks can make the output
+look nicer in some cases.
+
+@node Comparing Three Files
+@chapter Comparing Three Files
+@cindex comparing three files
+@cindex format of @command{diff3} output
+
+Use the program @command{diff3} to compare three files and show any
+differences among them. (@command{diff3} can also merge files; see
+@ref{diff3 Merging}).
+
+The ``normal'' @command{diff3} output format shows each hunk of
+differences without surrounding context. Hunks are labeled depending
+on whether they are two-way or three-way, and lines are annotated by
+their location in the input files.
+
+@xref{Invoking diff3}, for more information on how to run @command{diff3}.
+
+@menu
+* Sample diff3 Input:: Sample @command{diff3} input for examples.
+* Example diff3 Normal:: Sample output in the normal format.
+* Detailed diff3 Normal:: A detailed description of normal output format.
+* diff3 Hunks:: The format of normal output format.
+@end menu
+
+@node Sample diff3 Input
+@section A Third Sample Input File
+@cindex @command{diff3} sample input
+@cindex sample input for @command{diff3}
+
+Here is a third sample file that will be used in examples to illustrate
+the output of @command{diff3} and how various options can change it. The
+first two files are the same that we used for @command{diff} (@pxref{Sample
+diff Input}). This is the third sample file, called @file{tao}:
+
+@example
+The Way that can be told of is not the eternal Way;
+The name that can be named is not the eternal name.
+The Nameless is the origin of Heaven and Earth;
+The named is the mother of all things.
+
+Therefore let there always be non-being,
+ so we may see their subtlety,
+And let there always be being,
+ so we may see their result.
+The two are the same,
+But after they are produced,
+ they have different names.
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+@end example
+
+@node Example diff3 Normal
+@section An Example of @command{diff3} Normal Format
+
+Here is the output of the command @samp{diff3 lao tzu tao}
+(@pxref{Sample diff3 Input}, for the complete contents of the files).
+Notice that it shows only the lines that are different among the three
+files.
+
+@example
+====2
+1:1,2c
+3:1,2c
+ The Way that can be told of is not the eternal Way;
+ The name that can be named is not the eternal name.
+2:0a
+====1
+1:4c
+ The Named is the mother of all things.
+2:2,3c
+3:4,5c
+ The named is the mother of all things.
+ @-
+====3
+1:8c
+2:7c
+ so we may see their outcome.
+3:9c
+ so we may see their result.
+====
+1:11a
+2:11,13c
+ They both may be called deep and profound.
+ Deeper and more profound,
+ The door of all subtleties!
+3:13,14c
+ @-
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+@end example
+
+@node Detailed diff3 Normal
+@section Detailed Description of @command{diff3} Normal Format
+
+Each hunk begins with a line marked @samp{====}. Three-way hunks have
+plain @samp{====} lines, and two-way hunks have @samp{1}, @samp{2}, or
+@samp{3} appended to specify which of the three input files differ in
+that hunk. The hunks contain copies of two or three sets of input
+lines each preceded by one or two commands identifying where the lines
+came from.
+
+Normally, two spaces precede each copy of an input line to distinguish
+it from the commands. But with the @option{--initial-tab} (@option{-T})
+option, @command{diff3} uses a tab instead of two spaces; this lines up
+tabs correctly. @xref{Tabs}, for more information.
+
+Commands take the following forms:
+
+@table @samp
+@item @var{file}:@var{l}a
+This hunk appears after line @var{l} of file @var{file}, and
+contains no lines in that file. To edit this file to yield the other
+files, one must append hunk lines taken from the other files. For
+example, @samp{1:11a} means that the hunk follows line 11 in the first
+file and contains no lines from that file.
+
+@item @var{file}:@var{r}c
+This hunk contains the lines in the range @var{r} of file @var{file}.
+The range @var{r} is a comma-separated pair of line numbers, or just one
+number if there is only one line. To edit this file to yield the
+other files, one must change the specified lines to be the lines taken
+from the other files. For example, @samp{2:11,13c} means that the hunk
+contains lines 11 through 13 from the second file.
+@end table
+
+If the last line in a set of input lines is incomplete
+(@pxref{Incomplete Lines}), it is distinguished on output from a full
+line by a following line that starts with @samp{\}.
+
+@node diff3 Hunks
+@section @command{diff3} Hunks
+@cindex hunks for @command{diff3}
+@cindex @command{diff3} hunks
+
+Groups of lines that differ in two or three of the input files are
+called @dfn{diff3 hunks}, by analogy with @command{diff} hunks
+(@pxref{Hunks}). If all three input files differ in a @command{diff3}
+hunk, the hunk is called a @dfn{three-way hunk}; if just two input files
+differ, it is a @dfn{two-way hunk}.
+
+As with @command{diff}, several solutions are possible. When comparing the
+files @samp{A}, @samp{B}, and @samp{C}, @command{diff3} normally finds
+@command{diff3} hunks by merging the two-way hunks output by the two
+commands @samp{diff A B} and @samp{diff A C}. This does not necessarily
+minimize the size of the output, but exceptions should be rare.
+
+For example, suppose @file{F} contains the three lines @samp{a},
+@samp{b}, @samp{f}, @file{G} contains the lines @samp{g}, @samp{b},
+@samp{g}, and @file{H} contains the lines @samp{a}, @samp{b},
+@samp{h}. @samp{diff3 F G H} might output the following:
+
+@example
+====2
+1:1c
+3:1c
+ a
+2:1c
+ g
+====
+1:3c
+ f
+2:3c
+ g
+3:3c
+ h
+@end example
+
+@noindent
+because it found a two-way hunk containing @samp{a} in the first and
+third files and @samp{g} in the second file, then the single line
+@samp{b} common to all three files, then a three-way hunk containing
+the last line of each file.
+
+@node diff3 Merging
+@chapter Merging From a Common Ancestor
+@cindex merging from a common ancestor
+
+When two people have made changes to copies of the same file,
+@command{diff3} can produce a merged output that contains both sets of
+changes together with warnings about conflicts.
+
+One might imagine programs with names like @command{diff4} and @command{diff5}
+to compare more than three files simultaneously, but in practice the
+need rarely arises. You can use @command{diff3} to merge three or more
+sets of changes to a file by merging two change sets at a time.
+
+@command{diff3} can incorporate changes from two modified versions into a
+common preceding version. This lets you merge the sets of changes
+represented by the two newer files. Specify the common ancestor version
+as the second argument and the two newer versions as the first and third
+arguments, like this:
+
+@example
+diff3 @var{mine} @var{older} @var{yours}
+@end example
+
+@noindent
+You can remember the order of the arguments by noting that they are in
+alphabetical order.
+
+@cindex conflict
+@cindex overlap
+You can think of this as subtracting @var{older} from @var{yours} and
+adding the result to @var{mine}, or as merging into @var{mine} the
+changes that would turn @var{older} into @var{yours}. This merging is
+well-defined as long as @var{mine} and @var{older} match in the
+neighborhood of each such change. This fails to be true when all three
+input files differ or when only @var{older} differs; we call this
+a @dfn{conflict}. When all three input files differ, we call the
+conflict an @dfn{overlap}.
+
+@command{diff3} gives you several ways to handle overlaps and conflicts.
+You can omit overlaps or conflicts, or select only overlaps,
+or mark conflicts with special @samp{<<<<<<<} and @samp{>>>>>>>} lines.
+
+@command{diff3} can output the merge results as an @command{ed} script that
+that can be applied to the first file to yield the merged output.
+However, it is usually better to have @command{diff3} generate the merged
+output directly; this bypasses some problems with @command{ed}.
+
+@menu
+* Which Changes:: Selecting changes to incorporate.
+* Marking Conflicts:: Marking conflicts.
+* Bypassing ed:: Generating merged output directly.
+* Merging Incomplete Lines:: How @command{diff3} merges incomplete lines.
+* Saving the Changed File:: Emulating System V behavior.
+@end menu
+
+@node Which Changes
+@section Selecting Which Changes to Incorporate
+@cindex overlapping change, selection of
+@cindex unmerged change
+
+You can select all unmerged changes from @var{older} to @var{yours} for merging
+into @var{mine} with the @option{--ed} (@option{-e}) option. You can
+select only the nonoverlapping unmerged changes with
+@option{--easy-only} (@option{-3}),
+and you can select only the overlapping changes with
+@option{--overlap-only} (@option{-x}).
+
+The @option{-e}, @option{-3} and @option{-x} options select only
+@dfn{unmerged changes}, i.e.@: changes where @var{mine} and @var{yours}
+differ; they ignore changes from @var{older} to @var{yours} where
+@var{mine} and @var{yours} are identical, because they assume that such
+changes have already been merged. If this assumption is not a safe
+one, you can use the @option{--show-all} (@option{-A}) option
+(@pxref{Marking Conflicts}).
+
+Here is the output of the command @command{diff3} with each of these three
+options (@pxref{Sample diff3 Input}, for the complete contents of the files).
+Notice that @option{-e} outputs the union of the disjoint sets of changes
+output by @option{-3} and @option{-x}.
+
+Output of @samp{diff3 -e lao tzu tao}:
+@example
+11a
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+.
+8c
+ so we may see their result.
+.
+@end example
+
+Output of @samp{diff3 -3 lao tzu tao}:
+@example
+8c
+ so we may see their result.
+.
+@end example
+
+Output of @samp{diff3 -x lao tzu tao}:
+@example
+11a
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+.
+@end example
+
+@node Marking Conflicts
+@section Marking Conflicts
+@cindex conflict marking
+@cindex @samp{<<<<<<<} for marking conflicts
+
+@command{diff3} can mark conflicts in the merged output by
+bracketing them with special marker lines. A conflict
+that comes from two files @var{A} and @var{B} is marked as follows:
+
+@example
+<<<<<<< @var{A}
+@r{lines from @var{A}}
+=======
+@r{lines from @var{B}}
+>>>>>>> @var{B}
+@end example
+
+A conflict that comes from three files @var{A}, @var{B} and @var{C} is
+marked as follows:
+
+@example
+<<<<<<< @var{A}
+@r{lines from @var{A}}
+||||||| @var{B}
+@r{lines from @var{B}}
+=======
+@r{lines from @var{C}}
+>>>>>>> @var{C}
+@end example
+
+The @option{--show-all} (@option{-A}) option acts like the @option{-e}
+option, except that it brackets conflicts, and it outputs all changes
+from @var{older} to @var{yours}, not just the unmerged changes. Thus,
+given the sample input files (@pxref{Sample diff3 Input}), @samp{diff3
+-A lao tzu tao} puts brackets around the conflict where only @file{tzu}
+differs:
+
+@example
+<<<<<<< tzu
+=======
+The Way that can be told of is not the eternal Way;
+The name that can be named is not the eternal name.
+>>>>>>> tao
+@end example
+
+And it outputs the three-way conflict as follows:
+
+@example
+<<<<<<< lao
+||||||| tzu
+They both may be called deep and profound.
+Deeper and more profound,
+The door of all subtleties!
+=======
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+>>>>>>> tao
+@end example
+
+The @option{--show-overlap} (@option{-E}) option outputs less information
+than the @option{--show-all} (@option{-A}) option, because it outputs only
+unmerged changes, and it never outputs the contents of the second
+file. Thus the @option{-E} option acts like the @option{-e} option,
+except that it brackets the first and third files from three-way
+overlapping changes. Similarly, @option{-X} acts like @option{-x}, except
+it brackets all its (necessarily overlapping) changes. For example,
+for the three-way overlapping change above, the @option{-E} and @option{-X}
+options output the following:
+
+@example
+<<<<<<< lao
+=======
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+>>>>>>> tao
+@end example
+
+If you are comparing files that have meaningless or uninformative names,
+you can use the @option{--label=@var{label}}
+option to show alternate names in the @samp{<<<<<<<}, @samp{|||||||}
+and @samp{>>>>>>>} brackets. This option can be given up to three
+times, once for each input file. Thus @samp{diff3 -A --label X
+--label Y --label Z A
+B C} acts like @samp{diff3 -A A B C}, except that the output looks like
+it came from files named @samp{X}, @samp{Y} and @samp{Z} rather than
+from files named @samp{A}, @samp{B} and @samp{C}.
+
+@node Bypassing ed
+@section Generating the Merged Output Directly
+@cindex merged @command{diff3} format
+
+With the @option{--merge} (@option{-m}) option, @command{diff3} outputs the
+merged file directly. This is more efficient than using @command{ed} to
+generate it, and works even with non-text files that @command{ed} would
+reject. If you specify @option{-m} without an @command{ed} script option,
+@option{-A} is assumed.
+
+For example, the command @samp{diff3 -m lao tzu tao}
+(@pxref{Sample diff3 Input} for a copy of the input files) would output
+the following:
+
+@example
+<<<<<<< tzu
+=======
+The Way that can be told of is not the eternal Way;
+The name that can be named is not the eternal name.
+>>>>>>> tao
+The Nameless is the origin of Heaven and Earth;
+The Named is the mother of all things.
+Therefore let there always be non-being,
+ so we may see their subtlety,
+And let there always be being,
+ so we may see their result.
+The two are the same,
+But after they are produced,
+ they have different names.
+<<<<<<< lao
+||||||| tzu
+They both may be called deep and profound.
+Deeper and more profound,
+The door of all subtleties!
+=======
+
+ -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+>>>>>>> tao
+@end example
+
+@node Merging Incomplete Lines
+@section How @command{diff3} Merges Incomplete Lines
+@cindex incomplete line merging
+
+With @option{-m}, incomplete lines (@pxref{Incomplete Lines}) are simply
+copied to the output as they are found; if the merged output ends in an
+conflict and one of the input files ends in an incomplete
+line, succeeding @samp{|||||||}, @samp{=======} or @samp{>>>>>>>}
+brackets appear somewhere other than the start of a line because
+they are appended to the incomplete line.
+
+Without @option{-m}, if an @command{ed} script option is specified and an
+incomplete line is found, @command{diff3} generates a warning and acts as
+if a newline had been present.
+
+@node Saving the Changed File
+@section Saving the Changed File
+@cindex System V @command{diff3} compatibility
+
+Traditional Unix @command{diff3} generates an @command{ed} script without the
+trailing @samp{w} and @samp{q} commands that save the changes.
+System V @command{diff3} generates these extra commands. @acronym{GNU}
+@command{diff3} normally behaves like traditional Unix
+@command{diff3}, but with the @option{-i} option it behaves like
+System V @command{diff3} and appends the @samp{w} and @samp{q}
+commands.
+
+The @option{-i} option requires one of the @command{ed} script options
+@option{-AeExX3}, and is incompatible with the merged output option
+@option{-m}.
+
+@node Interactive Merging
+@chapter Interactive Merging with @command{sdiff}
+@cindex diff merging
+@cindex interactive merging
+
+With @command{sdiff}, you can merge two files interactively based on a
+side-by-side @option{-y} format comparison (@pxref{Side by Side}). Use
+@option{--output=@var{file}} (@option{-o @var{file}}) to specify where to
+put the merged text. @xref{Invoking sdiff}, for more details on the
+options to @command{sdiff}.
+
+Another way to merge files interactively is to use the Emacs Lisp
+package @command{emerge}. @xref{Emerge, , Emerge, emacs, The
+@acronym{GNU} Emacs Manual}, for more information.
+
+@menu
+* sdiff Option Summary:: Summary of @command{sdiff} options.
+* Merge Commands:: Merging two files interactively.
+@end menu
+
+@node sdiff Option Summary
+@section Specifying @command{diff} Options to @command{sdiff}
+@cindex @command{sdiff} output format
+
+The following @command{sdiff} options have the same meaning as for
+@command{diff}. @xref{diff Options}, for the use of these options.
+
+@example
+-a -b -d -i -t -v
+-B -E -I @var{regexp} -Z
+
+--expand-tabs
+--ignore-blank-lines --ignore-case
+--ignore-matching-lines=@var{regexp} --ignore-space-change
+--ignore-tab-expansion --ignore-trailing-space
+--left-column --minimal --speed-large-files
+--strip-trailing-cr --suppress-common-lines
+--tabsize=@var{columns} --text --version --width=@var{columns}
+@end example
+
+For historical reasons, @command{sdiff} has alternate names for some
+options. The @option{-l} option is equivalent to the
+@option{--left-column} option, and similarly @option{-s} is equivalent
+to @option{--suppress-common-lines}. The meaning of the @command{sdiff}
+@option{-w} and @option{-W} options is interchanged from that of
+@command{diff}: with @command{sdiff}, @option{-w @var{columns}} is
+equivalent to @option{--width=@var{columns}}, and @option{-W} is
+equivalent to @option{--ignore-all-space}. @command{sdiff} without the
+@option{-o} option is equivalent to @command{diff} with the
+@option{--side-by-side} (@option{-y}) option (@pxref{Side by Side}).
+
+@node Merge Commands
+@section Merge Commands
+@cindex merge commands
+@cindex merging interactively
+
+Groups of common lines, with a blank gutter, are copied from the first
+file to the output. After each group of differing lines, @command{sdiff}
+prompts with @samp{%} and pauses, waiting for one of the following
+commands. Follow each command with @key{RET}.
+
+@table @samp
+@item e
+Discard both versions.
+Invoke a text editor on an empty temporary file,
+then copy the resulting file to the output.
+
+@item eb
+Concatenate the two versions, edit the result in a temporary file,
+then copy the edited result to the output.
+
+@item ed
+Like @samp{eb}, except precede each version with a header that
+shows what file and lines the version came from.
+
+@item el
+@itemx e1
+Edit a copy of the left version, then copy the result to the output.
+
+@item er
+@itemx e2
+Edit a copy of the right version, then copy the result to the output.
+
+@item l
+@itemx 1
+Copy the left version to the output.
+
+@item q
+Quit.
+
+@item r
+@itemx 2
+Copy the right version to the output.
+
+@item s
+Silently copy common lines.
+
+@item v
+Verbosely copy common lines. This is the default.
+@end table
+
+@vindex EDITOR
+The text editor invoked is specified by the @env{EDITOR} environment
+variable if it is set. The default is system-dependent.
+
+@node Merging with patch
+@chapter Merging with @command{patch}
+
+@command{patch} takes comparison output produced by @command{diff} and applies
+the differences to a copy of the original file, producing a patched
+version. With @command{patch}, you can distribute just the changes to a
+set of files instead of distributing the entire file set; your
+correspondents can apply @command{patch} to update their copy of the files
+with your changes. @command{patch} automatically determines the diff
+format, skips any leading or trailing headers, and uses the headers to
+determine which file to patch. This lets your correspondents feed a
+mail message containing a difference listing directly to
+@command{patch}.
+
+@command{patch} detects and warns about common problems like forward
+patches. It saves any patches that it could not apply. It can also maintain a
+@code{patchlevel.h} file to ensure that your correspondents apply
+diffs in the proper order.
+
+@command{patch} accepts a series of diffs in its standard input, usually
+separated by headers that specify which file to patch. It applies
+@command{diff} hunks (@pxref{Hunks}) one by one. If a hunk does not
+exactly match the original file, @command{patch} uses heuristics to try to
+patch the file as well as it can. If no approximate match can be found,
+@command{patch} rejects the hunk and skips to the next hunk. @command{patch}
+normally replaces each file @var{f} with its new version, putting reject
+hunks (if any) into @samp{@var{f}.rej}.
+
+@xref{Invoking patch}, for detailed information on the options to
+@command{patch}.
+
+@menu
+* patch Input:: Selecting the type of @command{patch} input.
+* Revision Control:: Getting files from @acronym{RCS}, @acronym{SCCS}, etc.
+* Imperfect:: Dealing with imperfect patches.
+* Creating and Removing:: Creating and removing files with a patch.
+* Patching Time Stamps:: Updating time stamps on patched files.
+* Multiple Patches:: Handling multiple patches in a file.
+* patch Directories:: Changing directory and stripping directories.
+* Backups:: Whether backup files are made.
+* Backup Names:: Backup file names.
+* Reject Names:: Reject file names.
+* patch Messages:: Messages and questions @command{patch} can produce.
+* patch and POSIX:: Conformance to the @acronym{POSIX} standard.
+* patch and Tradition:: @acronym{GNU} versus traditional @command{patch}.
+@end menu
+
+@node patch Input
+@section Selecting the @command{patch} Input Format
+@cindex @command{patch} input format
+
+@command{patch} normally determines which @command{diff} format the patch
+file uses by examining its contents. For patch files that contain
+particularly confusing leading text, you might need to use one of the
+following options to force @command{patch} to interpret the patch file as a
+certain format of diff. The output formats listed here are the only
+ones that @command{patch} can understand.
+
+@table @option
+@item -c
+@itemx --context
+context diff.
+
+@item -e
+@itemx --ed
+@command{ed} script.
+
+@item -n
+@itemx --normal
+normal diff.
+
+@item -u
+@itemx --unified
+unified diff.
+@end table
+
+@node Revision Control
+@section Revision Control
+@cindex revision control
+@cindex version control
+@cindex @acronym{RCS}
+@cindex ClearCase
+@cindex @acronym{SCCS}
+
+If a nonexistent input file is under a revision control system
+supported by @command{patch}, @command{patch} normally asks the user
+whether to get (or check out) the file from the revision control
+system. Patch currently supports @acronym{RCS}, ClearCase and
+@acronym{SCCS}. Under @acronym{RCS} and @acronym{SCCS},
+@command{patch} also asks when the input file is read-only and matches
+the default version in the revision control system.
+
+@vindex PATCH_GET
+The @option{--get=@var{num}} (@option{-g @var{num}}) option affects access
+to files under supported revision control systems. If @var{num} is
+positive, @command{patch} gets the file without asking the user; if
+zero, @command{patch} neither asks the user nor gets the file; and if
+negative, @command{patch} asks the user before getting the file. The
+default value of @var{num} is given by the value of the
+@env{PATCH_GET} environment variable if it is set; if not, the default
+value is zero if @command{patch} is conforming to @acronym{POSIX}, negative
+otherwise. @xref{patch and POSIX}.
+
+@vindex VERSION_CONTROL
+The choice of revision control system is unaffected by the
+@env{VERSION_CONTROL} environment variable (@pxref{Backup Names}).
+
+@node Imperfect
+@section Applying Imperfect Patches
+@cindex imperfect patch application
+
+@command{patch} tries to skip any leading text in the patch file,
+apply the diff, and then skip any trailing text. Thus you can feed a
+mail message directly to @command{patch}, and it should work. If the
+entire diff is indented by a constant amount of white space,
+@command{patch} automatically ignores the indentation. If a context
+diff contains trailing carriage return on each line, @command{patch}
+automatically ignores the carriage return. If a context diff has been
+encapsulated by prepending @w{@samp{- }} to lines beginning with @samp{-}
+as per @uref{ftp://ftp.isi.edu/in-notes/rfc934.txt, Internet RFC 934},
+@command{patch} automatically unencapsulates the input.
+
+However, certain other types of imperfect input require user
+intervention or testing.
+
+@menu
+* Changed White Space:: When tabs and spaces don't match exactly.
+* Reversed Patches:: Applying reversed patches correctly.
+* Inexact:: Helping @command{patch} find close matches.
+* Dry Runs:: Predicting what @command{patch} will do.
+@end menu
+
+@node Changed White Space
+@subsection Applying Patches with Changed White Space
+@cindex white space in patches
+
+Sometimes mailers, editors, or other programs change spaces into tabs,
+or vice versa. If this happens to a patch file or an input file, the
+files might look the same, but @command{patch} will not be able to match
+them properly. If this problem occurs, use the @option{-l} or
+@option{--ignore-white-space} option, which makes @command{patch} compare
+blank characters (i.e.@: spaces and tabs) loosely so that any nonempty
+sequence of blanks in the patch file matches any nonempty sequence of
+blanks in the input files. Non-blank
+characters must still match exactly. Each line of the context must
+still match a line in the input file.
+
+@node Reversed Patches
+@subsection Applying Reversed Patches
+@cindex reversed patches
+
+Sometimes people run @command{diff} with the new file first instead of
+second. This creates a diff that is ``reversed''. To apply such
+patches, give @command{patch} the @option{--reverse} (@option{-R}) option.
+@command{patch} then attempts to swap each hunk around before applying it.
+Rejects come out in the swapped format.
+
+Often @command{patch} can guess that the patch is reversed. If the first
+hunk of a patch fails, @command{patch} reverses the hunk to see if it can
+apply it that way. If it can, @command{patch} asks you if you want to have
+the @option{-R} option set; if it can't, @command{patch} continues to apply
+the patch normally. This method cannot detect a reversed patch if it is
+a normal diff and the first command is an append (which should have been
+a delete) since appends always succeed, because a null context matches
+anywhere. But most patches add or change lines rather than delete them,
+so most reversed normal diffs begin with a delete, which fails, and
+@command{patch} notices.
+
+If you apply a patch that you have already applied, @command{patch} thinks
+it is a reversed patch and offers to un-apply the patch. This could be
+construed as a feature. If you did this inadvertently and you don't
+want to un-apply the patch, just answer @samp{n} to this offer and to
+the subsequent ``apply anyway'' question---or type @kbd{C-c} to kill the
+@command{patch} process.
+
+@node Inexact
+@subsection Helping @command{patch} Find Inexact Matches
+@cindex inexact patches
+@cindex fuzz factor when patching
+
+For context diffs, and to a lesser extent normal diffs, @command{patch} can
+detect when the line numbers mentioned in the patch are incorrect, and
+it attempts to find the correct place to apply each hunk of the patch.
+As a first guess, it takes the line number mentioned in the hunk, plus
+or minus any offset used in applying the previous hunk. If that is not
+the correct place, @command{patch} scans both forward and backward for a
+set of lines matching the context given in the hunk.
+
+First @command{patch} looks for a place where all lines of the context
+match. If it cannot find such a place, and it is reading a context or
+unified diff, and the maximum fuzz factor is set to 1 or more, then
+@command{patch} makes another scan, ignoring the first and last line of
+context. If that fails, and the maximum fuzz factor is set to 2 or
+more, it makes another scan, ignoring the first two and last two lines
+of context are ignored. It continues similarly if the maximum fuzz
+factor is larger.
+
+The @option{--fuzz=@var{lines}} (@option{-F @var{lines}}) option sets the
+maximum fuzz factor to @var{lines}. This option only applies to context
+and unified diffs; it ignores up to @var{lines} lines while looking for
+the place to install a hunk. Note that a larger fuzz factor increases
+the odds of making a faulty patch. The default fuzz factor is 2; there
+is no point to setting it to more than the number of lines of context
+in the diff, ordinarily 3.
+
+If @command{patch} cannot find a place to install a hunk of the patch, it
+writes the hunk out to a reject file (@pxref{Reject Names}, for information
+on how reject files are named). It writes out rejected hunks in context
+format no matter what form the input patch is in. If the input is a
+normal or @command{ed} diff, many of the contexts are simply null. The
+line numbers on the hunks in the reject file may be different from those
+in the patch file: they show the approximate location where @command{patch}
+thinks the failed hunks belong in the new file rather than in the old
+one.
+
+If the @option{--verbose} option is given, then
+as it completes each hunk @command{patch} tells you whether the hunk
+succeeded or failed, and if it failed, on which line (in the new file)
+@command{patch} thinks the hunk should go. If this is different from the
+line number specified in the diff, it tells you the offset. A single
+large offset @emph{may} indicate that @command{patch} installed a hunk in
+the wrong place. @command{patch} also tells you if it used a fuzz factor
+to make the match, in which case you should also be slightly suspicious.
+
+@command{patch} cannot tell if the line numbers are off in an @command{ed}
+script, and can only detect wrong line numbers in a normal diff when it
+finds a change or delete command. It may have the same problem with a
+context diff using a fuzz factor equal to or greater than the number of
+lines of context shown in the diff (typically 3). In these cases, you
+should probably look at a context diff between your original and patched
+input files to see if the changes make sense. Compiling without errors
+is a pretty good indication that the patch worked, but not a guarantee.
+
+A patch against an empty file applies to a nonexistent file, and vice
+versa. @xref{Creating and Removing}.
+
+@command{patch} usually produces the correct results, even when it must
+make many guesses. However, the results are guaranteed only when
+the patch is applied to an exact copy of the file that the patch was
+generated from.
+
+@node Dry Runs
+@subsection Predicting what @command{patch} will do
+@cindex testing @command{patch}
+@cindex dry runs for @command{patch}
+
+It may not be obvious in advance what @command{patch} will do with a
+complicated or poorly formatted patch. If you are concerned that the
+input might cause @command{patch} to modify the wrong files, you can
+use the @option{--dry-run} option, which causes @command{patch} to
+print the results of applying patches without actually changing any
+files. You can then inspect the diagnostics generated by the dry run
+to see whether @command{patch} will modify the files that you expect.
+If the patch does not do what you want, you can modify the patch (or
+the other options to @command{patch}) and try another dry run. Once
+you are satisfied with the proposed patch you can apply it by invoking
+@command{patch} as before, but this time without the
+@option{--dry-run} option.
+
+@node Creating and Removing
+@section Creating and Removing Files
+@cindex creating files
+@cindex empty files, removing
+@cindex removing empty files
+
+Sometimes when comparing two directories, a file may exist in one
+directory but not the other. If you give @command{diff} the
+@option{--new-file} (@option{-N}) option, or if you supply an old or
+new file that is named @file{/dev/null} or is empty and is dated the
+Epoch (1970-01-01 00:00:00 UTC), @command{diff} outputs a patch that
+adds or deletes the contents of this file. When given such a patch,
+@command{patch} normally creates a new file or removes the old file.
+However, when conforming to @acronym{POSIX} (@pxref{patch and POSIX}),
+@command{patch} does not remove the old file, but leaves it empty.
+The @option{--remove-empty-files} (@option{-E}) option causes
+@command{patch} to remove output files that are empty after applying a
+patch, even if the patch does not appear to be one that removed the
+file.
+
+If the patch appears to create a file that already exists,
+@command{patch} asks for confirmation before applying the patch.
+
+@node Patching Time Stamps
+@section Updating Time Stamps on Patched Files
+@cindex time stamps on patched files
+
+When @command{patch} updates a file, it normally sets the file's
+last-modified time stamp to the current time of day. If you are using
+@command{patch} to track a software distribution, this can cause
+@command{make} to incorrectly conclude that a patched file is out of
+date. For example, if @file{syntax.c} depends on @file{syntax.y}, and
+@command{patch} updates @file{syntax.c} and then @file{syntax.y}, then
+@file{syntax.c} will normally appear to be out of date with respect to
+@file{syntax.y} even though its contents are actually up to date.
+
+The @option{--set-utc} (@option{-Z}) option causes @command{patch} to
+set a patched file's modification and access times to the time stamps
+given in context diff headers. If the context diff headers do not
+specify a time zone, they are assumed to use Coordinated Universal
+Time (@acronym{UTC}, often known as @acronym{GMT}).
+
+The @option{--set-time} (@option{-T}) option acts like @option{-Z} or
+@option{--set-utc}, except that it assumes that the context diff
+headers' time stamps use local time instead of @acronym{UTC}. This option
+is not recommended, because patches using local time cannot easily be
+used by people in other time zones, and because local time stamps are
+ambiguous when local clocks move backwards during daylight-saving time
+adjustments. If the context diff headers specify a time zone, this
+option is equivalent to @option{--set-utc} (@option{-Z}).
+
+@command{patch} normally refrains from setting a file's time stamps if
+the file's original last-modified time stamp does not match the time
+given in the diff header, of if the file's contents do not exactly
+match the patch. However, if the @option{--force} (@option{-f})
+option is given, the file's time stamps are set regardless.
+
+Due to the limitations of the current @command{diff} format,
+@command{patch} cannot update the times of files whose contents have
+not changed. Also, if you set file time stamps to values other than
+the current time of day, you should also remove (e.g., with @samp{make
+clean}) all files that depend on the patched files, so that later
+invocations of @command{make} do not get confused by the patched
+files' times.
+
+@node Multiple Patches
+@section Multiple Patches in a File
+@cindex multiple patches
+@cindex intuiting file names from patches
+
+If the patch file contains more than one patch, and if you do not
+specify an input file on the command line, @command{patch} tries to
+apply each patch as if they came from separate patch files. This
+means that it determines the name of the file to patch for each patch,
+and that it examines the leading text before each patch for file names
+and prerequisite revision level (@pxref{Making Patches}, for more on
+that topic).
+
+@command{patch} uses the following rules to intuit a file name from
+the leading text before a patch. First, @command{patch} takes an
+ordered list of candidate file names as follows:
+
+@itemize @bullet
+@item
+If the header is that of a context diff, @command{patch} takes the old
+and new file names in the header. A name is ignored if it does not
+have enough slashes to satisfy the @option{-p@var{num}} or
+@option{--strip=@var{num}} option. The name @file{/dev/null} is also
+ignored.
+
+@item
+If there is an @samp{Index:} line in the leading garbage and if either
+the old and new names are both absent or if @command{patch} is
+conforming to @acronym{POSIX}, @command{patch} takes the name in the
+@samp{Index:} line.
+
+@item
+For the purpose of the following rules, the candidate file names are
+considered to be in the order (old, new, index), regardless of the
+order that they appear in the header.
+@end itemize
+
+@noindent
+Then @command{patch} selects a file name from the candidate list as
+follows:
+
+@itemize @bullet
+@item
+If some of the named files exist, @command{patch} selects the first
+name if conforming to @acronym{POSIX}, and the best name otherwise.
+
+@item
+If @command{patch} is not ignoring @acronym{RCS}, ClearCase, and @acronym{SCCS}
+(@pxref{Revision Control}), and no named files exist but an @acronym{RCS},
+ClearCase, or @acronym{SCCS} master is found, @command{patch} selects the
+first named file with an @acronym{RCS}, ClearCase, or @acronym{SCCS} master.
+
+@item
+If no named files exist, no @acronym{RCS}, ClearCase, or @acronym{SCCS} master
+was found, some names are given, @command{patch} is not conforming to
+@acronym{POSIX}, and the patch appears to create a file, @command{patch}
+selects the best name requiring the creation of the fewest
+directories.
+
+@item
+If no file name results from the above heuristics, you are asked for
+the name of the file to patch, and @command{patch} selects that name.
+@end itemize
+
+To determine the @dfn{best} of a nonempty list of file names,
+@command{patch} first takes all the names with the fewest path name
+components; of those, it then takes all the names with the shortest
+basename; of those, it then takes all the shortest names; finally, it
+takes the first remaining name.
+
+@xref{patch and POSIX}, to see whether @command{patch} is conforming
+to @acronym{POSIX}.
+
+@node patch Directories
+@section Applying Patches in Other Directories
+@cindex directories and patch
+@cindex patching directories
+
+The @option{--directory=@var{directory}} (@option{-d @var{directory}})
+option to @command{patch} makes directory @var{directory} the current
+directory for interpreting both file names in the patch file, and file
+names given as arguments to other options (such as @option{-B} and
+@option{-o}). For example, while in a mail reading program, you can patch
+a file in the @file{/usr/src/emacs} directory directly from a message
+containing the patch like this:
+
+@example
+| patch -d /usr/src/emacs
+@end example
+
+Sometimes the file names given in a patch contain leading directories,
+but you keep your files in a directory different from the one given in
+the patch. In those cases, you can use the
+@option{--strip=@var{number}} (@option{-p@var{number}})
+option to set the file name strip count to @var{number}. The strip
+count tells @command{patch} how many slashes, along with the directory
+names between them, to strip from the front of file names. A sequence
+of one or more adjacent slashes is counted as a single slash. By
+default, @command{patch} strips off all leading directories, leaving
+just the base file names.
+
+For example, suppose the file name in the patch file is
+@file{/gnu/src/emacs/etc/NEWS}. Using @option{-p0} gives the
+entire file name unmodified, @option{-p1} gives
+@file{gnu/src/emacs/etc/NEWS} (no leading slash), @option{-p4} gives
+@file{etc/NEWS}, and not specifying @option{-p} at all gives @file{NEWS}.
+
+@command{patch} looks for each file (after any slashes have been stripped)
+in the current directory, or if you used the @option{-d @var{directory}}
+option, in that directory.
+
+@node Backups
+@section Backup Files
+@cindex backup file strategy
+
+Normally, @command{patch} creates a backup file if the patch does not
+exactly match the original input file, because in that case the
+original data might not be recovered if you undo the patch with
+@samp{patch -R} (@pxref{Reversed Patches}). However, when conforming
+to @acronym{POSIX}, @command{patch} does not create backup files by
+default. @xref{patch and POSIX}.
+
+The @option{--backup} (@option{-b}) option causes @command{patch} to
+make a backup file regardless of whether the patch matches the
+original input. The @option{--backup-if-mismatch} option causes
+@command{patch} to create backup files for mismatches files; this is
+the default when not conforming to @acronym{POSIX}. The
+@option{--no-backup-if-mismatch} option causes @command{patch} to not
+create backup files, even for mismatched patches; this is the default
+when conforming to @acronym{POSIX}.
+
+When backing up a file that does not exist, an empty, unreadable
+backup file is created as a placeholder to represent the nonexistent
+file.
+
+@node Backup Names
+@section Backup File Names
+@cindex backup file names
+
+Normally, @command{patch} renames an original input file into a backup
+file by appending to its name the extension @samp{.orig}, or @samp{~}
+if using @samp{.orig} would make the backup file name too
+long.@footnote{A coding error in @acronym{GNU} @command{patch} version
+2.5.4 causes it to always use @samp{~}, but this should be fixed in
+the next release.} The @option{-z @var{backup-suffix}} or
+@option{--suffix=@var{backup-suffix}} option causes @command{patch} to
+use @var{backup-suffix} as the backup extension instead.
+
+@vindex SIMPLE_BACKUP_SUFFIX
+Alternately, you can specify the extension for backup files with the
+@env{SIMPLE_BACKUP_SUFFIX} environment variable, which the options
+override.
+
+@command{patch} can also create numbered backup files the way
+@acronym{GNU} Emacs does. With this method, instead of having a
+single backup of each file, @command{patch} makes a new backup file
+name each time it patches a file. For example, the backups of a file
+named @file{sink} would be called, successively, @file{sink.~1~},
+@file{sink.~2~}, @file{sink.~3~}, etc.
+
+@vindex PATCH_VERSION_CONTROL
+@vindex VERSION_CONTROL
+The @option{-V @var{backup-style}} or
+@option{--version-control=@var{backup-style}} option takes as an
+argument a method for creating backup file names. You can alternately
+control the type of backups that @command{patch} makes with the
+@env{PATCH_VERSION_CONTROL} environment variable, which the
+@option{-V} option overrides. If @env{PATCH_VERSION_CONTROL} is not
+set, the @env{VERSION_CONTROL} environment variable is used instead.
+Please note that these options and variables control backup file
+names; they do not affect the choice of revision control system
+(@pxref{Revision Control}).
+
+The values of these environment variables and the argument to the
+@option{-V} option are like the @acronym{GNU} Emacs @code{version-control}
+variable (@pxref{Backup Names, , , emacs, The @acronym{GNU} Emacs Manual},
+for more information on backup versions in Emacs). They also
+recognize synonyms that are more descriptive. The valid values are
+listed below; unique abbreviations are acceptable.
+
+@table @option
+@item t
+@itemx numbered
+Always make numbered backups.
+
+@item nil
+@itemx existing
+Make numbered backups of files that already have them, simple backups of
+the others. This is the default.
+
+@item never
+@itemx simple
+Always make simple backups.
+@end table
+
+You can also tell @command{patch} to prepend a prefix, such as a
+directory name, to produce backup file names. The
+@option{--prefix=@var{prefix}} (@option{-B @var{prefix}}) option makes backup
+files by prepending @var{prefix} to them. The
+@option{--basename-prefix=@var{prefix}} (@option{-Y @var{prefix}}) prepends
+@var{prefix} to the last file name component of backup file names
+instead; for example, @option{-Y ~} causes the backup name for
+@file{dir/file.c} to be @file{dir/~file.c}. If you use either of
+these prefix options, the suffix-based options are ignored.
+
+If you specify the output file with the @option{-o} option, that file is
+the one that is backed up, not the input file.
+
+Options that affect the names of backup files do not affect whether
+backups are made. For example, if you specify the
+@option{--no-backup-if-mismatch} option, none of the options described
+in this section have any affect, because no backups are made.
+
+@node Reject Names
+@section Reject File Names
+@cindex reject file names
+
+The names for reject files (files containing patches that
+@command{patch} could not find a place to apply) are normally the name
+of the output file with @samp{.rej} appended (or @samp{#} if using
+@samp{.rej} would make the backup file name too long).
+
+Alternatively, you can tell @command{patch} to place all of the rejected
+patches in a single file. The @option{-r @var{reject-file}} or
+@option{--reject-file=@var{reject-file}} option uses @var{reject-file} as
+the reject file name.
+
+@node patch Messages
+@section Messages and Questions from @command{patch}
+@cindex @command{patch} messages and questions
+@cindex diagnostics from @command{patch}
+@cindex messages from @command{patch}
+
+@command{patch} can produce a variety of messages, especially if it
+has trouble decoding its input. In a few situations where it's not
+sure how to proceed, @command{patch} normally prompts you for more
+information from the keyboard. There are options to produce more or
+fewer messages, to have it not ask for keyboard input, and to
+affect the way that file names are quoted in messages.
+
+@menu
+* More or Fewer Messages:: Controlling the verbosity of @command{patch}.
+* patch and Keyboard Input:: Inhibiting keyboard input.
+* patch Quoting Style:: Quoting file names in diagnostics.
+@end menu
+
+@command{patch} exits with status 0 if all hunks are applied successfully,
+1 if some hunks cannot be applied, and 2 if there is more serious trouble.
+When applying a set of patches in a loop, you should check the
+exit status, so you don't apply a later patch to a partially patched
+file.
+
+@node More or Fewer Messages
+@subsection Controlling the Verbosity of @command{patch}
+@cindex verbose messages from @command{patch}
+@cindex inhibit messages from @command{patch}
+
+You can cause @command{patch} to produce more messages by using the
+@option{--verbose} option. For example, when you give this option,
+the message @samp{Hmm...} indicates that @command{patch} is reading text in
+the patch file, attempting to determine whether there is a patch in that
+text, and if so, what kind of patch it is.
+
+You can inhibit all terminal output from @command{patch}, unless an error
+occurs, by using the @option{-s}, @option{--quiet}, or @option{--silent}
+option.
+
+@node patch and Keyboard Input
+@subsection Inhibiting Keyboard Input
+@cindex keyboard input to @command{patch}
+
+There are two ways you can prevent @command{patch} from asking you any
+questions. The @option{--force} (@option{-f}) option assumes that you know
+what you are doing. It causes @command{patch} to do the following:
+
+@itemize @bullet
+@item
+Skip patches that do not contain file names in their headers.
+
+@item
+Patch files even though they have the wrong version for the
+@samp{Prereq:} line in the patch;
+
+@item
+Assume that patches are not reversed even if they look like they are.
+@end itemize
+
+@noindent
+The @option{--batch} (@option{-t}) option is similar to @option{-f}, in that
+it suppresses questions, but it makes somewhat different assumptions:
+
+@itemize @bullet
+@item
+Skip patches that do not contain file names in their headers
+(the same as @option{-f}).
+
+@item
+Skip patches for which the file has the wrong version for the
+@samp{Prereq:} line in the patch;
+
+@item
+Assume that patches are reversed if they look like they are.
+@end itemize
+
+@node patch Quoting Style
+@subsection @command{patch} Quoting Style
+@cindex quoting style
+
+When @command{patch} outputs a file name in a diagnostic message, it
+can format the name in any of several ways. This can be useful to
+output file names unambiguously, even if they contain punctuation or
+special characters like newlines. The
+@option{--quoting-style=@var{word}} option controls how names are
+output. The @var{word} should be one of the following:
+
+@table @samp
+@item literal
+Output names as-is.
+@item shell
+Quote names for the shell if they contain shell metacharacters or would
+cause ambiguous output.
+@item shell-always
+Quote names for the shell, even if they would normally not require quoting.
+@item c
+Quote names as for a C language string.
+@item escape
+Quote as with @samp{c} except omit the surrounding double-quote
+characters.
+@c The following are not yet implemented in patch 2.5.4.
+@c @item clocale
+@c Quote as with @samp{c} except use quotation marks appropriate for the
+@c locale.
+@c @item locale
+@c @c Use @t instead of @samp to avoid duplicate quoting in some output styles.
+@c Like @samp{clocale}, but quote @t{'like this'} instead of @t{"like
+@c this"} in the default C locale. This looks nicer on many displays.
+@end table
+
+@vindex QUOTING_STYLE
+You can specify the default value of the @option{--quoting-style}
+option with the environment variable @env{QUOTING_STYLE}. If that
+environment variable is not set, the default value is @samp{shell},
+but this default may change in a future version of @command{patch}.
+
+@node patch and POSIX
+@section @command{patch} and the @acronym{POSIX} Standard
+@cindex @acronym{POSIX}
+
+@vindex POSIXLY_CORRECT
+If you specify the @option{--posix} option, or set the
+@env{POSIXLY_CORRECT} environment variable, @command{patch} conforms
+more strictly to the @acronym{POSIX} standard, as follows:
+
+@itemize @bullet
+@item
+Take the first existing file from the list (old, new, index)
+when intuiting file names from diff headers. @xref{Multiple Patches}.
+
+@item
+Do not remove files that are removed by a diff.
+@xref{Creating and Removing}.
+
+@item
+Do not ask whether to get files from @acronym{RCS}, ClearCase, or
+@acronym{SCCS}. @xref{Revision Control}.
+
+@item
+Require that all options precede the files in the command line.
+
+@item
+Do not backup files, even when there is a mismatch. @xref{Backups}.
+
+@end itemize
+
+@node patch and Tradition
+@section @acronym{GNU} @command{patch} and Traditional @command{patch}
+@cindex traditional @command{patch}
+
+The current version of @acronym{GNU} @command{patch} normally follows the
+@acronym{POSIX} standard. @xref{patch and POSIX}, for the few exceptions
+to this general rule.
+
+Unfortunately, @acronym{POSIX} redefined the behavior of @command{patch} in
+several important ways. You should be aware of the following
+differences if you must interoperate with traditional @command{patch},
+or with @acronym{GNU} @command{patch} version 2.1 and earlier.
+
+@itemize @bullet
+@item
+In traditional @command{patch}, the @option{-p} option's operand was
+optional, and a bare @option{-p} was equivalent to @option{-p0}. The
+@option{-p} option now requires an operand, and @option{-p@ 0} is now
+equivalent to @option{-p0}. For maximum compatibility, use options
+like @option{-p0} and @option{-p1}.
+
+Also, traditional @command{patch} simply counted slashes when
+stripping path prefixes; @command{patch} now counts pathname
+components. That is, a sequence of one or more adjacent slashes now
+counts as a single slash. For maximum portability, avoid sending
+patches containing @file{//} in file names.
+
+@item
+In traditional @command{patch}, backups were enabled by default. This
+behavior is now enabled with the @option{--backup} (@option{-b})
+option.
+
+Conversely, in @acronym{POSIX} @command{patch}, backups are never made,
+even when there is a mismatch. In @acronym{GNU} @command{patch}, this
+behavior is enabled with the @option{--no-backup-if-mismatch} option,
+or by conforming to @acronym{POSIX}.
+
+The @option{-b@ @var{suffix}} option of traditional @command{patch} is
+equivalent to the @samp{-b -z@ @var{suffix}} options of @acronym{GNU}
+@command{patch}.
+
+@item
+Traditional @command{patch} used a complicated (and incompletely
+documented) method to intuit the name of the file to be patched from
+the patch header. This method did not conform to @acronym{POSIX}, and had
+a few gotchas. Now @command{patch} uses a different, equally
+complicated (but better documented) method that is optionally
+@acronym{POSIX}-conforming; we hope it has fewer gotchas. The two methods
+are compatible if the file names in the context diff header and the
+@samp{Index:} line are all identical after prefix-stripping. Your
+patch is normally compatible if each header's file names all contain
+the same number of slashes.
+
+@item
+When traditional @command{patch} asked the user a question, it sent
+the question to standard error and looked for an answer from the first
+file in the following list that was a terminal: standard error,
+standard output, @file{/dev/tty}, and standard input. Now
+@command{patch} sends questions to standard output and gets answers
+from @file{/dev/tty}. Defaults for some answers have been changed so
+that @command{patch} never goes into an infinite loop when using
+default answers.
+
+@item
+Traditional @command{patch} exited with a status value that counted
+the number of bad hunks, or with status 1 if there was real trouble.
+Now @command{patch} exits with status 1 if some hunks failed, or with
+2 if there was real trouble.
+
+@item
+Limit yourself to the following options when sending instructions
+meant to be executed by anyone running @acronym{GNU} @command{patch},
+traditional @command{patch}, or a @command{patch} that conforms to
+@acronym{POSIX}. Spaces are significant in the following list, and
+operands are required.
+
+@example
+@option{-c}
+@option{-d @var{dir}}
+@option{-D @var{define}}
+@option{-e}
+@option{-l}
+@option{-n}
+@option{-N}
+@option{-o @var{outfile}}
+@option{-p@var{num}}
+@option{-R}
+@option{-r @var{rejectfile}}
+@end example
+
+@end itemize
+
+@node Making Patches
+@chapter Tips for Making and Using Patches
+
+Use some common sense when making and using patches. For example,
+when sending bug fixes to a program's maintainer, send several small
+patches, one per independent subject, instead of one large,
+harder-to-digest patch that covers all the subjects.
+
+Here are some other things you should keep in mind if you are going to
+distribute patches for updating a software package.
+
+@menu
+* Tips for Patch Producers:: Advice for making patches.
+* Tips for Patch Consumers:: Advice for using patches.
+* Avoiding Common Mistakes:: Avoiding common mistakes when using @command{patch}.
+* Generating Smaller Patches:: How to generate smaller patches.
+@end menu
+
+@node Tips for Patch Producers
+@section Tips for Patch Producers
+@cindex patch producer tips
+
+To create a patch that changes an older version of a package into a
+newer version, first make a copy of the older and newer versions in
+adjacent subdirectories. It is common to do that by unpacking
+@command{tar} archives of the two versions.
+
+To generate the patch, use the command @samp{diff -Naur @var{old}
+@var{new}} where @var{old} and @var{new} identify the old and new
+directories. The names @var{old} and @var{new} should not contain any
+slashes. The @option{-N} option lets the patch create and remove
+files; @option{-a} lets the patch update non-text files; @option{-u}
+generates useful time stamps and enough context; and @option{-r} lets
+the patch update subdirectories. Here is an example command, using
+Bourne shell syntax:
+
+@example
+diff -Naur gcc-3.0.3 gcc-3.0.4
+@end example
+
+Tell your recipients how to apply the patches. This should include
+which working directory to use, and which @command{patch} options to
+use; the option @samp{-p1} is recommended. Test your procedure by
+pretending to be a recipient and applying your patches to a copy of
+the original files.
+
+@xref{Avoiding Common Mistakes}, for how to avoid common mistakes when
+generating a patch.
+
+@node Tips for Patch Consumers
+@section Tips for Patch Consumers
+@cindex patch consumer tips
+
+A patch producer should tell recipients how to apply the patches, so
+the first rule of thumb for a patch consumer is to follow the
+instructions supplied with the patch.
+
+@acronym{GNU} @command{diff} can analyze files with arbitrarily long lines
+and files that end in incomplete lines. However, older versions of
+@command{patch} cannot patch such files. If you are having trouble
+applying such patches, try upgrading to a recent version of @acronym{GNU}
+@command{patch}.
+
+@node Avoiding Common Mistakes
+@section Avoiding Common Mistakes
+@cindex common mistakes with patches
+@cindex patch, common mistakes
+
+When producing a patch for multiple files, apply @command{diff} to
+directories whose names do not have slashes. This reduces confusion
+when the patch consumer specifies the @option{-p@var{number}} option,
+since this option can have surprising results when the old and new
+file names have different numbers of slashes. For example, do not
+send a patch with a header that looks like this:
+
+@example
+diff -Naur v2.0.29/prog/README prog/README
+--- v2.0.29/prog/README 2002-03-10 23:30:39.942229878 -0800
++++ prog/README 2002-03-17 20:49:32.442260588 -0800
+@end example
+
+@noindent
+because the two file names have different numbers of slashes, and
+different versions of @command{patch} interpret the file names
+differently. To avoid confusion, send output that looks like this
+instead:
+
+@example
+diff -Naur v2.0.29/prog/README v2.0.30/prog/README
+--- v2.0.29/prog/README 2002-03-10 23:30:39.942229878 -0800
++++ v2.0.30/prog/README 2002-03-17 20:49:32.442260588 -0800
+@end example
+
+Make sure you have specified the file names correctly, either in a
+context diff header or with an @samp{Index:} line. Take care to not send out
+reversed patches, since these make people wonder whether they have
+already applied the patch.
+
+Avoid sending patches that compare backup file names like
+@file{README.orig} or @file{README~}, since this might confuse
+@command{patch} into patching a backup file instead of the real file.
+Instead, send patches that compare the same base file names in
+different directories, e.g.@: @file{old/README} and @file{new/README}.
+
+To save people from partially applying a patch before other patches that
+should have gone before it, you can make the first patch in the patch
+file update a file with a name like @file{patchlevel.h} or
+@file{version.c}, which contains a patch level or version number. If
+the input file contains the wrong version number, @command{patch} will
+complain immediately.
+
+An even clearer way to prevent this problem is to put a @samp{Prereq:}
+line before the patch. If the leading text in the patch file contains a
+line that starts with @samp{Prereq:}, @command{patch} takes the next word
+from that line (normally a version number) and checks whether the next
+input file contains that word, preceded and followed by either
+white space or a newline. If not, @command{patch} prompts you for
+confirmation before proceeding. This makes it difficult to accidentally
+apply patches in the wrong order.
+
+@node Generating Smaller Patches
+@section Generating Smaller Patches
+@cindex patches, shrinking
+
+The simplest way to generate a patch is to use @samp{diff -Naur}
+(@pxref{Tips for Patch Producers}), but you might be able to reduce
+the size of the patch by renaming or removing some files before making
+the patch. If the older version of the package contains any files
+that the newer version does not, or if any files have been renamed
+between the two versions, make a list of @command{rm} and @command{mv}
+commands for the user to execute in the old version directory before
+applying the patch. Then run those commands yourself in the scratch
+directory.
+
+If there are any files that you don't need to include in the patch
+because they can easily be rebuilt from other files (for example,
+@file{TAGS} and output from @command{yacc} and @command{makeinfo}),
+exclude them from the patch by giving @command{diff} the @option{-x
+@var{pattern}} option (@pxref{Comparing Directories}). If you want
+your patch to modify a derived file because your recipients lack tools
+to build it, make sure that the patch for the derived file follows any
+patches for files that it depends on, so that the recipients' time
+stamps will not confuse @command{make}.
+
+Now you can create the patch using @samp{diff -Naur}. Make sure to
+specify the scratch directory first and the newer directory second.
+
+Add to the top of the patch a note telling the user any @command{rm} and
+@command{mv} commands to run before applying the patch. Then you can
+remove the scratch directory.
+
+You can also shrink the patch size by using fewer lines of context,
+but bear in mind that @command{patch} typically needs at least two
+lines for proper operation when patches do not exactly match the input
+files.
+
+@node Invoking cmp
+@chapter Invoking @command{cmp}
+@cindex invoking @command{cmp}
+@cindex @command{cmp} invocation
+
+The @command{cmp} command compares two files, and if they differ,
+tells the first byte and line number where they differ or reports
+that one file is a prefix of the other. Bytes and
+lines are numbered starting with 1. The arguments of @command{cmp}
+are as follows:
+
+@example
+cmp @var{options}@dots{} @var{from-file} @r{[}@var{to-file} @r{[}@var{from-skip} @r{[}@var{to-skip}@r{]}@r{]}@r{]}
+@end example
+
+The file name @file{-} is always the standard input. @command{cmp}
+also uses the standard input if one file name is omitted. The
+@var{from-skip} and @var{to-skip} operands specify how many bytes to
+ignore at the start of each file; they are equivalent to the
+@option{--ignore-initial=@var{from-skip}:@var{to-skip}} option.
+
+By default, @command{cmp} outputs nothing if the two files have the
+same contents. If one file is a prefix of the other, @command{cmp}
+prints to standard error a message of the following form:
+
+@example
+cmp: EOF on @var{shorter-file}
+@end example
+
+Otherwise, @command{cmp} prints to standard output a message of the
+following form:
+
+@example
+@var{from-file} @var{to-file} differ: char @var{byte-number}, line @var{line-number}
+@end example
+
+The message formats can differ outside the @acronym{POSIX} locale.
+Also, @acronym{POSIX} allows the @acronym{EOF} message to be followed
+by a blank and some additional information.
+
+An exit status of 0 means no differences were found, 1 means some
+differences were found, and 2 means trouble.
+
+@menu
+* cmp Options:: Summary of options to @command{cmp}.
+@end menu
+
+@node cmp Options
+@section Options to @command{cmp}
+@cindex @command{cmp} options
+@cindex options for @command{cmp}
+
+Below is a summary of all of the options that @acronym{GNU}
+@command{cmp} accepts. Most options have two equivalent names, one of
+which is a single letter preceded by @samp{-}, and the other of which
+is a long name preceded by @samp{--}. Multiple single letter options
+(unless they take an argument) can be combined into a single command
+line word: @option{-bl} is equivalent to @option{-b -l}.
+
+@table @option
+@item -b
+@itemx --print-bytes
+Print the differing bytes. Display control bytes as a
+@samp{^} followed by a letter of the alphabet and precede bytes
+that have the high bit set with @samp{M-} (which stands for ``meta'').
+
+@item --help
+Output a summary of usage and then exit.
+
+@item -i @var{skip}
+@itemx --ignore-initial=@var{skip}
+Ignore any differences in the first @var{skip} bytes of the input
+files. Treat files with fewer than @var{skip} bytes as if they are
+empty. If @var{skip} is of the form
+@option{@var{from-skip}:@var{to-skip}}, skip the first @var{from-skip}
+bytes of the first input file and the first @var{to-skip} bytes of the
+second.
+
+@item -l
+@itemx --verbose
+Output the (decimal) byte numbers and (octal) values of all differing bytes,
+instead of the default standard output.
+Each output line contains a differing byte's number relative to the
+start of the input, followed by the differing byte values.
+Byte numbers start at 1.
+Also, output the @acronym{EOF} message if one file is shorter than the other.
+
+@item -n @var{count}
+@itemx --bytes=@var{count}
+Compare at most @var{count} input bytes.
+
+@item -s
+@itemx --quiet
+@itemx --silent
+Do not print anything; only return an exit status indicating whether
+the files differ.
+
+@item -v
+@itemx --version
+Output version information and then exit.
+@end table
+
+In the above table, operands that are byte counts are normally
+decimal, but may be preceded by @samp{0} for octal and @samp{0x} for
+hexadecimal.
+
+A byte count can be followed by a suffix to specify a multiple of that
+count; in this case an omitted integer is understood to be 1. A bare
+size letter, or one followed by @samp{iB}, specifies a multiple using
+powers of 1024. A size letter followed by @samp{B} specifies powers
+of 1000 instead. For example, @option{-n 4M} and @option{-n 4MiB} are
+equivalent to @option{-n 4194304}, whereas @option{-n 4MB} is
+equivalent to @option{-n 4000000}. This notation is upward compatible
+with the @uref{http://www.bipm.fr/enus/3_SI/si-prefixes.html, SI
+prefixes} for decimal multiples and with the
+@uref{http://physics.nist.gov/cuu/Units/binary.html, IEC 60027-2
+prefixes for binary multiples}.
+
+The following suffixes are defined. Large sizes like @code{1Y} may be
+rejected by your computer due to limitations of its arithmetic.
+
+@table @samp
+@item kB
+@cindex kilobyte, definition of
+kilobyte: @math{10^3 = 1000}.
+@item k
+@itemx K
+@itemx KiB
+@cindex kibibyte, definition of
+kibibyte: @math{2^10 = 1024}. @samp{K} is special: the SI prefix is
+@samp{k} and the IEC 60027-2 prefix is @samp{Ki}, but tradition and
+@acronym{POSIX} use @samp{k} to mean @samp{KiB}.
+@item MB
+@cindex megabyte, definition of
+megabyte: @math{10^6 = 1,000,000}.
+@item M
+@itemx MiB
+@cindex mebibyte, definition of
+mebibyte: @math{2^20 = 1,048,576}.
+@item GB
+@cindex gigabyte, definition of
+gigabyte: @math{10^9 = 1,000,000,000}.
+@item G
+@itemx GiB
+@cindex gibibyte, definition of
+gibibyte: @math{2^30 = 1,073,741,824}.
+@item TB
+@cindex terabyte, definition of
+terabyte: @math{10^12 = 1,000,000,000,000}.
+@item T
+@itemx TiB
+@cindex tebibyte, definition of
+tebibyte: @math{2^40 = 1,099,511,627,776}.
+@item PB
+@cindex petabyte, definition of
+petabyte: @math{10^15 = 1,000,000,000,000,000}.
+@item P
+@itemx PiB
+@cindex pebibyte, definition of
+pebibyte: @math{2^50 = 1,125,899,906,842,624}.
+@item EB
+@cindex exabyte, definition of
+exabyte: @math{10^18 = 1,000,000,000,000,000,000}.
+@item E
+@itemx EiB
+@cindex exbibyte, definition of
+exbibyte: @math{2^60 = 1,152,921,504,606,846,976}.
+@item ZB
+@cindex zettabyte, definition of
+zettabyte: @math{10^21 = 1,000,000,000,000,000,000,000}
+@item Z
+@itemx ZiB
+@math{2^70 = 1,180,591,620,717,411,303,424}.
+(@samp{Zi} is a GNU extension to IEC 60027-2.)
+@item YB
+@cindex yottabyte, definition of
+yottabyte: @math{10^24 = 1,000,000,000,000,000,000,000,000}.
+@item Y
+@itemx YiB
+@math{2^80 = 1,208,925,819,614,629,174,706,176}.
+(@samp{Yi} is a GNU extension to IEC 60027-2.)
+@end table
+
+@node Invoking diff
+@chapter Invoking @command{diff}
+@cindex invoking @command{diff}
+@cindex @command{diff} invocation
+
+The format for running the @command{diff} command is:
+
+@example
+diff @var{options}@dots{} @var{files}@dots{}
+@end example
+
+In the simplest case, two file names @var{from-file} and
+@var{to-file} are given, and @command{diff} compares the contents of
+@var{from-file} and @var{to-file}. A file name of @file{-} stands for
+the standard input.
+
+If one file is a directory and the other is not, @command{diff} compares
+the file in the directory whose name is that of the non-directory.
+The non-directory file must not be @file{-}.
+
+If two file names are given and both are directories,
+@command{diff} compares corresponding files in both directories, in
+alphabetical order; this comparison is not recursive unless the
+@option{--recursive} (@option{-r}) option is given. @command{diff} never
+compares the actual contents of a directory as if it were a file. The
+file that is fully specified may not be standard input, because standard
+input is nameless and the notion of ``file with the same name'' does not
+apply.
+
+If the @option{--from-file=@var{file}} option is given, the number of
+file names is arbitrary, and @var{file} is compared to each named file.
+Similarly, if the @option{--to-file=@var{file}} option is given, each
+named file is compared to @var{file}.
+
+@command{diff} options begin with @samp{-}, so normally file names
+may not begin with @samp{-}. However, @option{--} as an
+argument by itself treats the remaining arguments as file names even if
+they begin with @samp{-}.
+
+An exit status of 0 means no differences were found, 1 means some
+differences were found, and 2 means trouble.
+
+@menu
+* diff Options:: Summary of options to @command{diff}.
+@end menu
+
+@node diff Options
+@section Options to @command{diff}
+@cindex @command{diff} options
+@cindex options for @command{diff}
+
+Below is a summary of all of the options that @acronym{GNU}
+@command{diff} accepts. Most options have two equivalent names, one
+of which is a single letter preceded by @samp{-}, and the other of
+which is a long name preceded by @samp{--}. Multiple single letter
+options (unless they take an argument) can be combined into a single
+command line word: @option{-ac} is equivalent to @option{-a -c}. Long
+named options can be abbreviated to any unique prefix of their name.
+Brackets ([ and ]) indicate that an option takes an optional argument.
+
+@table @option
+@item -a
+@itemx --text
+Treat all files as text and compare them line-by-line, even if they
+do not seem to be text. @xref{Binary}.
+
+@item -b
+@itemx --ignore-space-change
+Ignore changes in amount of white space. @xref{White Space}.
+
+@item -B
+@itemx --ignore-blank-lines
+Ignore changes that just insert or delete blank lines. @xref{Blank
+Lines}.
+
+@item --binary
+Read and write data in binary mode. @xref{Binary}.
+
+@item -c
+Use the context output format, showing three lines of context.
+@xref{Context Format}.
+
+@item --color [=@var{when}]
+@cindex color, distinguishing different context
+Specify whether to use color for distinguishing different contexts,
+like header, added or removed lines. @var{when} may be omitted, or
+one of:
+@itemize @bullet
+@item none
+@vindex none @r{color option}
+Do not use color at all. This is the default when no --color option
+is specified.
+@item auto
+@vindex auto @r{color option}
+@cindex terminal, using color iff
+Use color only if standard output is a terminal.
+@item always
+@vindex always @r{color option}
+Always use color.
+@end itemize
+Specifying @option{--color} and no @var{when} is equivalent to
+@option{--color=auto}.
+
+@item -C @var{lines}
+@itemx --context@r{[}=@var{lines}@r{]}
+Use the context output format, showing @var{lines} (an integer) lines of
+context, or three if @var{lines} is not given. @xref{Context Format}.
+For proper operation, @command{patch} typically needs at least two lines of
+context.
+
+For compatibility @command{diff} also supports an obsolete option
+syntax @option{-@var{lines}} that has effect when combined with
+@option{-c}, @option{-p}, or @option{-u}. New scripts should use
+@option{-U @var{lines}} (@option{-C @var{lines}}) instead.
+
+@item --changed-group-format=@var{format}
+Use @var{format} to output a line group containing differing lines from
+both files in if-then-else format. @xref{Line Group Formats}.
+
+@item -d
+@itemx --minimal
+Change the algorithm perhaps find a smaller set of changes. This makes
+@command{diff} slower (sometimes much slower). @xref{diff Performance}.
+
+@item -D @var{name}
+@itemx --ifdef=@var{name}
+Make merged @samp{#ifdef} format output, conditional on the preprocessor
+macro @var{name}. @xref{If-then-else}.
+
+@item -e
+@itemx --ed
+Make output that is a valid @command{ed} script. @xref{ed Scripts}.
+
+@item -E
+@itemx --ignore-tab-expansion
+Ignore changes due to tab expansion.
+@xref{White Space}.
+
+@item -f
+@itemx --forward-ed
+Make output that looks vaguely like an @command{ed} script but has changes
+in the order they appear in the file. @xref{Forward ed}.
+
+@item -F @var{regexp}
+@itemx --show-function-line=@var{regexp}
+In context and unified format, for each hunk of differences, show some
+of the last preceding line that matches @var{regexp}. @xref{Specified
+Headings}.
+
+@item --from-file=@var{file}
+Compare @var{file} to each operand; @var{file} may be a directory.
+
+@item --help
+Output a summary of usage and then exit.
+
+@item --horizon-lines=@var{lines}
+Do not discard the last @var{lines} lines of the common prefix
+and the first @var{lines} lines of the common suffix.
+@xref{diff Performance}.
+
+@item -i
+@itemx --ignore-case
+Ignore changes in case; consider upper- and lower-case letters
+equivalent. @xref{Case Folding}.
+
+@item -I @var{regexp}
+@itemx --ignore-matching-lines=@var{regexp}
+Ignore changes that just insert or delete lines that match @var{regexp}.
+@xref{Specified Lines}.
+
+@item --ignore-file-name-case
+Ignore case when comparing file names. For example, recursive
+comparison of @file{d} to @file{e} might compare the contents of
+@file{d/Init} and @file{e/inIt}. At the top level, @samp{diff d inIt}
+might compare the contents of @file{d/Init} and @file{inIt}.
+@xref{Comparing Directories}.
+
+@item -l
+@itemx --paginate
+Pass the output through @command{pr} to paginate it. @xref{Pagination}.
+
+@item -L @var{label}
+@itemx --label=@var{label}
+Use @var{label} instead of the file name in the context format
+(@pxref{Context Format}) and unified format (@pxref{Unified Format})
+headers. @xref{RCS}.
+
+@item --left-column
+Print only the left column of two common lines in side by side format.
+@xref{Side by Side Format}.
+
+@item --line-format=@var{format}
+Use @var{format} to output all input lines in if-then-else format.
+@xref{Line Formats}.
+
+@item -n
+@itemx --rcs
+Output @acronym{RCS}-format diffs; like @option{-f} except that each command
+specifies the number of lines affected. @xref{RCS}.
+
+@item -N
+@itemx --new-file
+If one file is missing, treat it as present but empty.
+@xref{Comparing Directories}.
+
+@item --new-group-format=@var{format}
+Use @var{format} to output a group of lines taken from just the second
+file in if-then-else format. @xref{Line Group Formats}.
+
+@item --new-line-format=@var{format}
+Use @var{format} to output a line taken from just the second file in
+if-then-else format. @xref{Line Formats}.
+
+@item --no-dereference
+Act on symbolic links themselves instead of what they point to.
+Two symbolic links are deemed equal only when each points to
+precisely the same name.
+
+@item --old-group-format=@var{format}
+Use @var{format} to output a group of lines taken from just the first
+file in if-then-else format. @xref{Line Group Formats}.
+
+@item --old-line-format=@var{format}
+Use @var{format} to output a line taken from just the first file in
+if-then-else format. @xref{Line Formats}.
+
+@item -p
+@itemx --show-c-function
+Show which C function each change is in. @xref{C Function Headings}.
+
+@item --palette=@var{palette}
+Specify what color palette to use when colored output is enabled. It
+defaults to @samp{rs=0:hd=1:ad=32:de=31:ln=36} for red deleted lines,
+green added lines, cyan line numbers, bold header.
+
+Supported capabilities are as follows.
+
+@table @code
+@item ad=32
+@vindex ad @r{capability}
+
+SGR substring for added lines.
+The default is green foreground.
+
+@item de=31
+@vindex de @r{capability}
+
+SGR substring for deleted lines.
+The default is red foreground.
+
+@item hd=1
+@vindex hd @r{capability}
+
+SGR substring for chunk header.
+The default is bold foreground.
+
+@item ln=36
+@vindex ln @r{capability}
+
+SGR substring for line numbers.
+The default is cyan foreground.
+@end table
+
+
+@item -q
+@itemx --brief
+Report only whether the files differ, not the details of the
+differences. @xref{Brief}.
+
+@item -r
+@itemx --recursive
+When comparing directories, recursively compare any subdirectories
+found. @xref{Comparing Directories}.
+
+@item -s
+@itemx --report-identical-files
+Report when two files are the same. @xref{Comparing Directories}.
+
+@item -S @var{file}
+@itemx --starting-file=@var{file}
+When comparing directories, start with the file @var{file}. This is
+used for resuming an aborted comparison. @xref{Comparing Directories}.
+
+@item --speed-large-files
+Use heuristics to speed handling of large files that have numerous
+scattered small changes. @xref{diff Performance}.
+
+@item --strip-trailing-cr
+Strip any trailing carriage return at the end of an input line.
+@xref{Binary}.
+
+@item --suppress-common-lines
+Do not print common lines in side by side format.
+@xref{Side by Side Format}.
+
+@item -t
+@itemx --expand-tabs
+Expand tabs to spaces in the output, to preserve the alignment of tabs
+in the input files. @xref{Tabs}.
+
+@item -T
+@itemx --initial-tab
+Output a tab rather than a space before the text of a line in normal or
+context format. This causes the alignment of tabs in the line to look
+normal. @xref{Tabs}.
+
+@item --tabsize=@var{columns}
+Assume that tab stops are set every @var{columns} (default 8) print
+columns. @xref{Tabs}.
+
+@item --suppress-blank-empty
+Suppress any blanks before newlines when printing the representation
+of an empty line, when outputting normal, context, or unified format.
+@xref{Trailing Blanks}.
+
+@item --to-file=@var{file}
+Compare each operand to @var{file}; @var{file} may be a directory.
+
+@item -u
+Use the unified output format, showing three lines of context.
+@xref{Unified Format}.
+
+@item --unchanged-group-format=@var{format}
+Use @var{format} to output a group of common lines taken from both files
+in if-then-else format. @xref{Line Group Formats}.
+
+@item --unchanged-line-format=@var{format}
+Use @var{format} to output a line common to both files in if-then-else
+format. @xref{Line Formats}.
+
+@item --unidirectional-new-file
+If a first file is missing, treat it as present but empty.
+@xref{Comparing Directories}.
+
+@item -U @var{lines}
+@itemx --unified@r{[}=@var{lines}@r{]}
+Use the unified output format, showing @var{lines} (an integer) lines of
+context, or three if @var{lines} is not given. @xref{Unified Format}.
+For proper operation, @command{patch} typically needs at least two lines of
+context.
+
+On older systems, @command{diff} supports an obsolete option
+@option{-@var{lines}} that has effect when combined with @option{-u}.
+@acronym{POSIX} 1003.1-2001 (@pxref{Standards conformance}) does not allow
+this; use @option{-U @var{lines}} instead.
+
+@item -v
+@itemx --version
+Output version information and then exit.
+
+@item -w
+@itemx --ignore-all-space
+Ignore white space when comparing lines. @xref{White Space}.
+
+@item -W @var{columns}
+@itemx --width=@var{columns}
+Output at most @var{columns} (default 130) print columns per line in
+side by side format. @xref{Side by Side Format}.
+
+@item -x @var{pattern}
+@itemx --exclude=@var{pattern}
+When comparing directories, ignore files and subdirectories whose basenames
+match @var{pattern}. @xref{Comparing Directories}.
+
+@item -X @var{file}
+@itemx --exclude-from=@var{file}
+When comparing directories, ignore files and subdirectories whose basenames
+match any pattern contained in @var{file}. @xref{Comparing Directories}.
+
+@item -y
+@itemx --side-by-side
+Use the side by side output format. @xref{Side by Side Format}.
+
+@item -Z
+@itemx --ignore-trailing-space
+Ignore white space at line end. @xref{White Space}.
+@end table
+
+@node Invoking diff3
+@chapter Invoking @command{diff3}
+@cindex invoking @command{diff3}
+@cindex @command{diff3} invocation
+
+The @command{diff3} command compares three files and outputs descriptions
+of their differences. Its arguments are as follows:
+
+@example
+diff3 @var{options}@dots{} @var{mine} @var{older} @var{yours}
+@end example
+
+The files to compare are @var{mine}, @var{older}, and @var{yours}.
+At most one of these three file names may be @file{-},
+which tells @command{diff3} to read the standard input for that file.
+
+An exit status of 0 means @command{diff3} was successful, 1 means some
+conflicts were found, and 2 means trouble.
+
+@menu
+* diff3 Options:: Summary of options to @command{diff3}.
+@end menu
+
+@node diff3 Options
+@section Options to @command{diff3}
+@cindex @command{diff3} options
+@cindex options for @command{diff3}
+
+Below is a summary of all of the options that @acronym{GNU} @command{diff3}
+accepts. Multiple single letter options (unless they take an argument)
+can be combined into a single command line argument.
+
+@table @option
+@item -a
+@itemx --text
+Treat all files as text and compare them line-by-line, even if they
+do not appear to be text. @xref{Binary}.
+
+@item -A
+@itemx --show-all
+Incorporate all unmerged changes from @var{older} to @var{yours} into
+@var{mine}, surrounding conflicts with bracket lines.
+@xref{Marking Conflicts}.
+
+@item --diff-program=@var{program}
+Use the compatible comparison program @var{program} to compare files
+instead of @command{diff}.
+
+@item -e
+@itemx --ed
+Generate an @command{ed} script that incorporates all the changes from
+@var{older} to @var{yours} into @var{mine}. @xref{Which Changes}.
+
+@item -E
+@itemx --show-overlap
+Like @option{-e}, except bracket lines from overlapping changes' first
+and third files.
+@xref{Marking Conflicts}.
+With @option{-E}, an overlapping change looks like this:
+
+@example
+<<<<<<< @var{mine}
+@r{lines from @var{mine}}
+=======
+@r{lines from @var{yours}}
+>>>>>>> @var{yours}
+@end example
+
+@item --help
+Output a summary of usage and then exit.
+
+@item -i
+Generate @samp{w} and @samp{q} commands at the end of the @command{ed}
+script for System V compatibility. This option must be combined with
+one of the @option{-AeExX3} options, and may not be combined with @option{-m}.
+@xref{Saving the Changed File}.
+
+@item --label=@var{label}
+Use the label @var{label} for the brackets output by the @option{-A},
+@option{-E} and @option{-X} options. This option may be given up to three
+times, one for each input file. The default labels are the names of
+the input files. Thus @samp{diff3 --label X --label Y --label Z -m A
+B C} acts like
+@samp{diff3 -m A B C}, except that the output looks like it came from
+files named @samp{X}, @samp{Y} and @samp{Z} rather than from files
+named @samp{A}, @samp{B} and @samp{C}. @xref{Marking Conflicts}.
+
+@item -m
+@itemx --merge
+Apply the edit script to the first file and send the result to standard
+output. Unlike piping the output from @command{diff3} to @command{ed}, this
+works even for binary files and incomplete lines. @option{-A} is assumed
+if no edit script option is specified. @xref{Bypassing ed}.
+
+@item --strip-trailing-cr
+Strip any trailing carriage return at the end of an input line.
+@xref{Binary}.
+
+@item -T
+@itemx --initial-tab
+Output a tab rather than two spaces before the text of a line in normal format.
+This causes the alignment of tabs in the line to look normal. @xref{Tabs}.
+
+@item -v
+@itemx --version
+Output version information and then exit.
+
+@item -x
+@itemx --overlap-only
+Like @option{-e}, except output only the overlapping changes.
+@xref{Which Changes}.
+
+@item -X
+Like @option{-E}, except output only the overlapping changes.
+In other words, like @option{-x}, except bracket changes as in @option{-E}.
+@xref{Marking Conflicts}.
+
+@item -3
+@itemx --easy-only
+Like @option{-e}, except output only the nonoverlapping changes.
+@xref{Which Changes}.
+@end table
+
+@node Invoking patch
+@chapter Invoking @command{patch}
+@cindex invoking @command{patch}
+@cindex @command{patch} invocation
+
+Normally @command{patch} is invoked like this:
+
+@example
+patch <@var{patchfile}
+@end example
+
+The full format for invoking @command{patch} is:
+
+@example
+patch @var{options}@dots{} @r{[}@var{origfile} @r{[}@var{patchfile}@r{]}@r{]}
+@end example
+
+You can also specify where to read the patch from with the @option{-i
+@var{patchfile}} or @option{--input=@var{patchfile}} option.
+If you do not specify @var{patchfile}, or if @var{patchfile} is
+@file{-}, @command{patch} reads the patch (that is, the @command{diff} output)
+from the standard input.
+
+If you do not specify an input file on the command line, @command{patch}
+tries to intuit from the @dfn{leading text} (any text in the patch
+that comes before the @command{diff} output) which file to edit.
+@xref{Multiple Patches}.
+
+By default, @command{patch} replaces the original input file with the
+patched version, possibly after renaming the original file into a
+backup file (@pxref{Backup Names}, for a description of how
+@command{patch} names backup files). You can also specify where to
+put the output with the @option{-o @var{file}} or
+@option{--output=@var{file}} option; however, do not use this option
+if @var{file} is one of the input files.
+
+@menu
+* patch Options:: Summary table of options to @command{patch}.
+@end menu
+
+@node patch Options
+@section Options to @command{patch}
+@cindex @command{patch} options
+@cindex options for @command{patch}
+
+Here is a summary of all of the options that @acronym{GNU} @command{patch}
+accepts. @xref{patch and Tradition}, for which of these options are
+safe to use in older versions of @command{patch}.
+
+Multiple single-letter options that do not take an argument can be
+combined into a single command line argument with only one dash.
+
+@table @option
+@item -b
+@itemx --backup
+Back up the original contents of each file, even if backups would
+normally not be made. @xref{Backups}.
+
+@item -B @var{prefix}
+@itemx --prefix=@var{prefix}
+Prepend @var{prefix} to backup file names. @xref{Backup Names}.
+
+@item --backup-if-mismatch
+Back up the original contents of each file if the patch does not
+exactly match the file. This is the default behavior when not
+conforming to @acronym{POSIX}. @xref{Backups}.
+
+@item --binary
+Read and write all files in binary mode, except for standard output
+and @file{/dev/tty}. This option has no effect on
+@acronym{POSIX}-conforming systems like @acronym{GNU}/Linux. On systems where
+this option makes a difference, the patch should be generated by
+@samp{diff -a --binary}. @xref{Binary}.
+
+@item -c
+@itemx --context
+Interpret the patch file as a context diff. @xref{patch Input}.
+
+@item -d @var{directory}
+@itemx --directory=@var{directory}
+Make directory @var{directory} the current directory for interpreting
+both file names in the patch file, and file names given as arguments to
+other options. @xref{patch Directories}.
+
+@item -D @var{name}
+@itemx --ifdef=@var{name}
+Make merged if-then-else output using @var{name}. @xref{If-then-else}.
+
+@item --dry-run
+Print the results of applying the patches without actually changing
+any files. @xref{Dry Runs}.
+
+@item -e
+@itemx --ed
+Interpret the patch file as an @command{ed} script. @xref{patch Input}.
+
+@item -E
+@itemx --remove-empty-files
+Remove output files that are empty after the patches have been applied.
+@xref{Creating and Removing}.
+
+@item -f
+@itemx --force
+Assume that the user knows exactly what he or she is doing, and do not
+ask any questions. @xref{patch Messages}.
+
+@item -F @var{lines}
+@itemx --fuzz=@var{lines}
+Set the maximum fuzz factor to @var{lines}. @xref{Inexact}.
+
+@item -g @var{num}
+@itemx --get=@var{num}
+If @var{num} is positive, get input files from a revision control
+system as necessary; if zero, do not get the files; if negative, ask
+the user whether to get the files. @xref{Revision Control}.
+
+@item --help
+Output a summary of usage and then exit.
+
+@item -i @var{patchfile}
+@itemx --input=@var{patchfile}
+Read the patch from @var{patchfile} rather than from standard input.
+@xref{patch Options}.
+
+@item -l
+@itemx --ignore-white-space
+Let any sequence of blanks (spaces or tabs) in the patch file match
+any sequence of blanks in the input file. @xref{Changed White Space}.
+
+@item -n
+@itemx --normal
+Interpret the patch file as a normal diff. @xref{patch Input}.
+
+@item -N
+@itemx --forward
+Ignore patches that @command{patch} thinks are reversed or already applied.
+See also @option{-R}. @xref{Reversed Patches}.
+
+@item --no-backup-if-mismatch
+Do not back up the original contents of files. This is the default
+behavior when conforming to @acronym{POSIX}. @xref{Backups}.
+
+@item -o @var{file}
+@itemx --output=@var{file}
+Use @var{file} as the output file name. @xref{patch Options}.
+
+@item -p@var{number}
+@itemx --strip=@var{number}
+Set the file name strip count to @var{number}. @xref{patch Directories}.
+
+@item --posix
+Conform to @acronym{POSIX}, as if the @env{POSIXLY_CORRECT} environment
+variable had been set. @xref{patch and POSIX}.
+
+@item --quoting-style=@var{word}
+Use style @var{word} to quote names in diagnostics, as if the
+@env{QUOTING_STYLE} environment variable had been set to @var{word}.
+@xref{patch Quoting Style}.
+
+@item -r @var{reject-file}
+@itemx --reject-file=@var{reject-file}
+Use @var{reject-file} as the reject file name. @xref{Reject Names}.
+
+@item -R
+@itemx --reverse
+Assume that this patch was created with the old and new files swapped.
+@xref{Reversed Patches}.
+
+@item -s
+@itemx --quiet
+@itemx --silent
+Work silently unless an error occurs. @xref{patch Messages}.
+
+@item -t
+@itemx --batch
+Do not ask any questions. @xref{patch Messages}.
+
+@item -T
+@itemx --set-time
+Set the modification and access times of patched files from time
+stamps given in context diff headers, assuming that the context diff
+headers use local time. @xref{Patching Time Stamps}.
+
+@item -u
+@itemx --unified
+Interpret the patch file as a unified diff. @xref{patch Input}.
+
+@item -v
+@itemx --version
+Output version information and then exit.
+
+@item -V @var{backup-style}
+@itemx --version=control=@var{backup-style}
+Select the naming convention for backup file names. @xref{Backup Names}.
+
+@item --verbose
+Print more diagnostics than usual. @xref{patch Messages}.
+
+@item -x @var{number}
+@itemx --debug=@var{number}
+Set internal debugging flags. Of interest only to @command{patch}
+patchers.
+
+@item -Y @var{prefix}
+@itemx --basename-prefix=@var{prefix}
+Prepend @var{prefix} to base names of backup files. @xref{Backup Names}.
+
+@item -z @var{suffix}
+@itemx --suffix=@var{suffix}
+Use @var{suffix} as the backup extension instead of @samp{.orig} or
+@samp{~}. @xref{Backup Names}.
+
+@item -Z
+@itemx --set-utc
+Set the modification and access times of patched files from time
+stamps given in context diff headers, assuming that the context diff
+headers use @acronym{UTC}. @xref{Patching Time Stamps}.
+
+@end table
+
+@node Invoking sdiff
+@chapter Invoking @command{sdiff}
+@cindex invoking @command{sdiff}
+@cindex @command{sdiff} invocation
+
+The @command{sdiff} command merges two files and interactively outputs the
+results. Its arguments are as follows:
+
+@example
+sdiff -o @var{outfile} @var{options}@dots{} @var{from-file} @var{to-file}
+@end example
+
+This merges @var{from-file} with @var{to-file}, with output to @var{outfile}.
+If @var{from-file} is a directory and @var{to-file} is not, @command{sdiff}
+compares the file in @var{from-file} whose file name is that of @var{to-file},
+and vice versa. @var{from-file} and @var{to-file} may not both be
+directories.
+
+@command{sdiff} options begin with @samp{-}, so normally @var{from-file}
+and @var{to-file} may not begin with @samp{-}. However, @option{--} as an
+argument by itself treats the remaining arguments as file names even if
+they begin with @samp{-}. You may not use @file{-} as an input file.
+
+@command{sdiff} without @option{--output} (@option{-o}) produces a
+side-by-side difference. This usage is obsolete; use the
+@option{--side-by-side} (@option{-y}) option of @command{diff} instead.
+
+An exit status of 0 means no differences were found, 1 means some
+differences were found, and 2 means trouble.
+
+@menu
+* sdiff Options:: Summary of options to @command{diff}.
+@end menu
+
+@node sdiff Options
+@section Options to @command{sdiff}
+@cindex @command{sdiff} options
+@cindex options for @command{sdiff}
+
+Below is a summary of all of the options that @acronym{GNU}
+@command{sdiff} accepts. Each option has two equivalent names, one of
+which is a single letter preceded by @samp{-}, and the other of which
+is a long name preceded by @samp{--}. Multiple single letter options
+(unless they take an argument) can be combined into a single command
+line argument. Long named options can be abbreviated to any unique
+prefix of their name.
+
+@table @option
+@item -a
+@itemx --text
+Treat all files as text and compare them line-by-line, even if they
+do not appear to be text. @xref{Binary}.
+
+@item -b
+@itemx --ignore-space-change
+Ignore changes in amount of white space. @xref{White Space}.
+
+@item -B
+@itemx --ignore-blank-lines
+Ignore changes that just insert or delete blank lines. @xref{Blank
+Lines}.
+
+@item -d
+@itemx --minimal
+Change the algorithm to perhaps find a smaller set of changes. This
+makes @command{sdiff} slower (sometimes much slower). @xref{diff
+Performance}.
+
+@item --diff-program=@var{program}
+Use the compatible comparison program @var{program} to compare files
+instead of @command{diff}.
+
+@item -E
+@itemx --ignore-tab-expansion
+Ignore changes due to tab expansion.
+@xref{White Space}.
+
+@item --help
+Output a summary of usage and then exit.
+
+@item -i
+@itemx --ignore-case
+Ignore changes in case; consider upper- and lower-case to be the same.
+@xref{Case Folding}.
+
+@item -I @var{regexp}
+@itemx --ignore-matching-lines=@var{regexp}
+Ignore changes that just insert or delete lines that match @var{regexp}.
+@xref{Specified Lines}.
+
+@item -l
+@itemx --left-column
+Print only the left column of two common lines.
+@xref{Side by Side Format}.
+
+@item -o @var{file}
+@itemx --output=@var{file}
+Put merged output into @var{file}. This option is required for merging.
+
+@item -s
+@itemx --suppress-common-lines
+Do not print common lines. @xref{Side by Side Format}.
+
+@item --speed-large-files
+Use heuristics to speed handling of large files that have numerous
+scattered small changes. @xref{diff Performance}.
+
+@item --strip-trailing-cr
+Strip any trailing carriage return at the end of an input line.
+@xref{Binary}.
+
+@item -t
+@itemx --expand-tabs
+Expand tabs to spaces in the output, to preserve the alignment of tabs
+in the input files. @xref{Tabs}.
+
+@item --tabsize=@var{columns}
+Assume that tab stops are set every @var{columns} (default 8) print
+columns. @xref{Tabs}.
+
+@item -v
+@itemx --version
+Output version information and then exit.
+
+@item -w @var{columns}
+@itemx --width=@var{columns}
+Output at most @var{columns} (default 130) print columns per line.
+@xref{Side by Side Format}. Note that for historical reasons, this
+option is @option{-W} in @command{diff}, @option{-w} in @command{sdiff}.
+
+@item -W
+@itemx --ignore-all-space
+Ignore white space when comparing lines. @xref{White Space}.
+Note that for historical reasons, this option is @option{-w} in @command{diff},
+@option{-W} in @command{sdiff}.
+
+@item -Z
+@itemx --ignore-trailing-space
+Ignore white space at line end. @xref{White Space}.
+@end table
+
+@node Standards conformance
+@chapter Standards conformance
+@cindex @acronym{POSIX}
+
+@vindex POSIXLY_CORRECT
+In a few cases, the @acronym{GNU} utilities' default behavior is
+incompatible with the @acronym{POSIX} standard. To suppress these
+incompatibilities, define the @env{POSIXLY_CORRECT} environment
+variable. Unless you are checking for @acronym{POSIX} conformance, you
+probably do not need to define @env{POSIXLY_CORRECT}.
+
+Normally options and operands can appear in any order, and programs act
+as if all the options appear before any operands. For example,
+@samp{diff lao tzu -C 2} acts like @samp{diff -C 2 lao tzu}, since
+@samp{2} is an option-argument of @option{-C}. However, if the
+@env{POSIXLY_CORRECT} environment variable is set, options must appear
+before operands, unless otherwise specified for a particular command.
+
+Newer versions of @acronym{POSIX} are occasionally incompatible with older
+versions. For example, older versions of @acronym{POSIX} allowed the
+command @samp{diff -c -10} to have the same meaning as @samp{diff -C
+10}, but @acronym{POSIX} 1003.1-2001 @samp{diff} no longer allows
+digit-string options like @option{-10}.
+
+@vindex _POSIX2_VERSION
+The @acronym{GNU} utilities normally conform to the version of @acronym{POSIX}
+that is standard for your system. To cause them to conform to a
+different version of @acronym{POSIX}, define the @env{_POSIX2_VERSION}
+environment variable to a value of the form @var{yyyymm} specifying
+the year and month the standard was adopted. Two values are currently
+supported for @env{_POSIX2_VERSION}: @samp{199209} stands for
+@acronym{POSIX} 1003.2-1992, and @samp{200112} stands for @acronym{POSIX}
+1003.1-2001. For example, if you are running older software that
+assumes an older version of @acronym{POSIX} and uses @samp{diff -c -10},
+you can work around the compatibility problems by setting
+@samp{_POSIX2_VERSION=199209} in your environment.
+
+@node Projects
+@chapter Future Projects
+
+Here are some ideas for improving @acronym{GNU} @command{diff} and
+@command{patch}. The @acronym{GNU} project has identified some
+improvements as potential programming projects for volunteers. You
+can also help by reporting any bugs that you find.
+
+If you are a programmer and would like to contribute something to the
+@acronym{GNU} project, please consider volunteering for one of these
+projects. If you are seriously contemplating work, please write to
+@email{gvc@@gnu.org} to coordinate with other volunteers.
+
+@menu
+* Shortcomings:: Suggested projects for improvements.
+* Bugs:: Reporting bugs.
+@end menu
+
+@node Shortcomings
+@section Suggested Projects for Improving @acronym{GNU} @command{diff} and @command{patch}
+@cindex projects for directories
+
+One should be able to use @acronym{GNU} @command{diff} to generate a
+patch from any pair of directory trees, and given the patch and a copy
+of one such tree, use @command{patch} to generate a faithful copy of
+the other. Unfortunately, some changes to directory trees cannot be
+expressed using current patch formats; also, @command{patch} does not
+handle some of the existing formats. These shortcomings motivate the
+following suggested projects.
+
+@menu
+* Internationalization:: Handling multibyte and varying-width characters.
+* Changing Structure:: Handling changes to the directory structure.
+* Special Files:: Handling symbolic links, device special files, etc.
+* Unusual File Names:: Handling file names that contain unusual characters.
+* Time Stamp Order:: Outputting diffs in time stamp order.
+* Ignoring Changes:: Ignoring certain changes while showing others.
+* Speedups:: Improving performance.
+@end menu
+
+@node Internationalization
+@subsection Handling Multibyte and Varying-Width Characters
+@cindex multibyte characters
+@cindex varying-width characters
+
+@command{diff}, @command{diff3} and @command{sdiff} treat each line of
+input as a string of unibyte characters. This can mishandle multibyte
+characters in some cases. For example, when asked to ignore spaces,
+@command{diff} does not properly ignore a multibyte space character.
+
+Also, @command{diff} currently assumes that each byte is one column
+wide, and this assumption is incorrect in some locales, e.g., locales
+that use UTF-8 encoding. This causes problems with the @option{-y} or
+@option{--side-by-side} option of @command{diff}.
+
+These problems need to be fixed without unduly affecting the
+performance of the utilities in unibyte environments.
+
+The IBM GNU/Linux Technology Center Internationalization Team has
+proposed
+@uref{http://oss.software.ibm.com/developer/opensource/linux/patches/i18n/diffutils-2.7.2-i18n-0.1.patch.gz,patches
+to support internationalized @command{diff}}.
+Unfortunately, these patches are incomplete and are to an older
+version of @command{diff}, so more work needs to be done in this area.
+
+@node Changing Structure
+@subsection Handling Changes to the Directory Structure
+@cindex directory structure changes
+
+@command{diff} and @command{patch} do not handle some changes to directory
+structure. For example, suppose one directory tree contains a directory
+named @samp{D} with some subsidiary files, and another contains a file
+with the same name @samp{D}. @samp{diff -r} does not output enough
+information for @command{patch} to transform the directory subtree into
+the file.
+
+There should be a way to specify that a file has been removed without
+having to include its entire contents in the patch file. There should
+also be a way to tell @command{patch} that a file was renamed, even if
+there is no way for @command{diff} to generate such information.
+There should be a way to tell @command{patch} that a file's time stamp
+has changed, even if its contents have not changed.
+
+These problems can be fixed by extending the @command{diff} output format
+to represent changes in directory structure, and extending @command{patch}
+to understand these extensions.
+
+@node Special Files
+@subsection Files that are Neither Directories Nor Regular Files
+@cindex special files
+
+Some files are neither directories nor regular files: they are unusual
+files like symbolic links, device special files, named pipes, and
+sockets. Currently, @command{diff} treats symbolic links as if they
+were the pointed-to files, except that a recursive @command{diff}
+reports an error if it detects infinite loops of symbolic links (e.g.,
+symbolic links to @file{..}). @command{diff} treats other special
+files like regular files if they are specified at the top level, but
+simply reports their presence when comparing directories. This means
+that @command{patch} cannot represent changes to such files. For
+example, if you change which file a symbolic link points to,
+@command{diff} outputs the difference between the two files, instead
+of the change to the symbolic link.
+
+@c This might not be a good idea; is it wise for root to install devices
+@c this way?
+@command{diff} should optionally report changes to special files specially,
+and @command{patch} should be extended to understand these extensions.
+
+@node Unusual File Names
+@subsection File Names that Contain Unusual Characters
+@cindex file names with unusual characters
+
+When a file name contains an unusual character like a newline or
+white space, @samp{diff -r} generates a patch that @command{patch} cannot
+parse. The problem is with format of @command{diff} output, not just with
+@command{patch}, because with odd enough file names one can cause
+@command{diff} to generate a patch that is syntactically correct but
+patches the wrong files. The format of @command{diff} output should be
+extended to handle all possible file names.
+
+@node Time Stamp Order
+@subsection Outputting Diffs in Time Stamp Order
+
+Applying @command{patch} to a multiple-file diff can result in files
+whose time stamps are out of order. @acronym{GNU} @command{patch} has
+options to restore the time stamps of the updated files
+(@pxref{Patching Time Stamps}), but sometimes it is useful to generate
+a patch that works even if the recipient does not have @acronym{GNU} patch,
+or does not use these options. One way to do this would be to
+implement a @command{diff} option to output diffs in time stamp order.
+
+@node Ignoring Changes
+@subsection Ignoring Certain Changes
+
+It would be nice to have a feature for specifying two strings, one in
+@var{from-file} and one in @var{to-file}, which should be considered to
+match. Thus, if the two strings are @samp{foo} and @samp{bar}, then if
+two lines differ only in that @samp{foo} in file 1 corresponds to
+@samp{bar} in file 2, the lines are treated as identical.
+
+It is not clear how general this feature can or should be, or
+what syntax should be used for it.
+
+A partial substitute is to filter one or both files before comparing,
+e.g.:
+
+@example
+sed 's/foo/bar/g' file1 | diff - file2
+@end example
+
+However, this outputs the filtered text, not the original.
+
+@node Speedups
+@subsection Improving Performance
+
+When comparing two large directory structures, one of which was
+originally copied from the other with time stamps preserved (e.g.,
+with @samp{cp -pR}), it would greatly improve performance if an option
+told @command{diff} to assume that two files with the same size and
+time stamps have the same content. @xref{diff Performance}.
+
+@node Bugs
+@section Reporting Bugs
+@cindex bug reports
+@cindex reporting bugs
+
+If you think you have found a bug in @acronym{GNU} @command{cmp},
+@command{diff}, @command{diff3}, or @command{sdiff}, please report it
+by electronic mail to the
+@uref{http://mail.gnu.org/mailman/listinfo/bug-diffutils,GNU utilities
+bug report mailing list} @email{bug-diffutils@@gnu.org}. Please send
+bug reports for @acronym{GNU} @command{patch} to
+@email{bug-patch@@gnu.org}. Send as precise a description of the
+problem as you can, including the output of the @option{--version}
+option and sample input files that produce the bug, if applicable. If
+you have a nontrivial fix for the bug, please send it as well. If you
+have a patch, please send it too. It may simplify the maintainer's
+job if the patch is relative to a recent test release, which you can
+find in the directory @uref{ftp://alpha.gnu.org/gnu/diffutils/}.
+
+@node Copying This Manual
+@appendix Copying This Manual
+@include fdl.texi
+
+@node Translations
+@appendix Translations of This Manual
+
+Nishio Futoshi of the GNUjdoc project has prepared a Japanese
+translation of this manual. Its most recent version can be found at
+@uref{http://openlab.ring.gr.jp/gnujdoc/cvsweb/cvsweb.cgi/gnujdoc/}.
+
+@node Index
+@appendix Index
+
+@printindex cp
+
+@bye
diff --git a/doc/fdl.texi b/doc/fdl.texi
new file mode 100644
index 0000000..9c3bbe5
--- /dev/null
+++ b/doc/fdl.texi
@@ -0,0 +1,505 @@
+@c The GNU Free Documentation License.
+@center Version 1.3, 3 November 2008
+
+@c This file is intended to be included within another document,
+@c hence no sectioning command or @node.
+
+@display
+Copyright @copyright{} 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
+@uref{http://fsf.org/}
+
+Everyone is permitted to copy and distribute verbatim copies
+of this license document, but changing it is not allowed.
+@end display
+
+@enumerate 0
+@item
+PREAMBLE
+
+The purpose of this License is to make a manual, textbook, or other
+functional and useful document @dfn{free} in the sense of freedom: to
+assure everyone the effective freedom to copy and redistribute it,
+with or without modifying it, either commercially or noncommercially.
+Secondarily, this License preserves for the author and publisher a way
+to get credit for their work, while not being considered responsible
+for modifications made by others.
+
+This License is a kind of ``copyleft'', which means that derivative
+works of the document must themselves be free in the same sense. It
+complements the GNU General Public License, which is a copyleft
+license designed for free software.
+
+We have designed this License in order to use it for manuals for free
+software, because free software needs free documentation: a free
+program should come with manuals providing the same freedoms that the
+software does. But this License is not limited to software manuals;
+it can be used for any textual work, regardless of subject matter or
+whether it is published as a printed book. We recommend this License
+principally for works whose purpose is instruction or reference.
+
+@item
+APPLICABILITY AND DEFINITIONS
+
+This License applies to any manual or other work, in any medium, that
+contains a notice placed by the copyright holder saying it can be
+distributed under the terms of this License. Such a notice grants a
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+refers to any such manual or work. Any member of the public is a
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+
+A ``Modified Version'' of the Document means any work containing the
+Document or a portion of it, either copied verbatim, or with
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+A ``Secondary Section'' is a named appendix or a front-matter section
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+
+The ``Invariant Sections'' are certain Secondary Sections whose titles
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+
+The ``Cover Texts'' are certain short passages of text that are listed,
+as Front-Cover Texts or Back-Cover Texts, in the notice that says that
+the Document is released under this License. A Front-Cover Text may
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+
+A ``Transparent'' copy of the Document means a machine-readable copy,
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+Examples of suitable formats for Transparent copies include plain
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+of transparent image formats include PNG, XCF and
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+
+The ``Title Page'' means, for a printed book, the title page itself,
+plus such following pages as are needed to hold, legibly, the material
+this License requires to appear in the title page. For works in
+formats which do not have any title page as such, ``Title Page'' means
+the text near the most prominent appearance of the work's title,
+preceding the beginning of the body of the text.
+
+The ``publisher'' means any person or entity that distributes copies
+of the Document to the public.
+
+A section ``Entitled XYZ'' means a named subunit of the Document whose
+title either is precisely XYZ or contains XYZ in parentheses following
+text that translates XYZ in another language. (Here XYZ stands for a
+specific section name mentioned below, such as ``Acknowledgements'',
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+of such a section when you modify the Document means that it remains a
+section ``Entitled XYZ'' according to this definition.
+
+The Document may include Warranty Disclaimers next to the notice which
+states that this License applies to the Document. These Warranty
+Disclaimers are considered to be included by reference in this
+License, but only as regards disclaiming warranties: any other
+implication that these Warranty Disclaimers may have is void and has
+no effect on the meaning of this License.
+
+@item
+VERBATIM COPYING
+
+You may copy and distribute the Document in any medium, either
+commercially or noncommercially, provided that this License, the
+copyright notices, and the license notice saying this License applies
+to the Document are reproduced in all copies, and that you add no other
+conditions whatsoever to those of this License. You may not use
+technical measures to obstruct or control the reading or further
+copying of the copies you make or distribute. However, you may accept
+compensation in exchange for copies. If you distribute a large enough
+number of copies you must also follow the conditions in section 3.
+
+You may also lend copies, under the same conditions stated above, and
+you may publicly display copies.
+
+@item
+COPYING IN QUANTITY
+
+If you publish printed copies (or copies in media that commonly have
+printed covers) of the Document, numbering more than 100, and the
+Document's license notice requires Cover Texts, you must enclose the
+copies in covers that carry, clearly and legibly, all these Cover
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+Copying with changes limited to the covers, as long as they preserve
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+
+If the required texts for either cover are too voluminous to fit
+legibly, you should put the first ones listed (as many as fit
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+
+If you publish or distribute Opaque copies of the Document numbering
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+
+It is requested, but not required, that you contact the authors of the
+Document well before redistributing any large number of copies, to give
+them a chance to provide you with an updated version of the Document.
+
+@item
+MODIFICATIONS
+
+You may copy and distribute a Modified Version of the Document under
+the conditions of sections 2 and 3 above, provided that you release
+the Modified Version under precisely this License, with the Modified
+Version filling the role of the Document, thus licensing distribution
+and modification of the Modified Version to whoever possesses a copy
+of it. In addition, you must do these things in the Modified Version:
+
+@enumerate A
+@item
+Use in the Title Page (and on the covers, if any) a title distinct
+from that of the Document, and from those of previous versions
+(which should, if there were any, be listed in the History section
+of the Document). You may use the same title as a previous version
+if the original publisher of that version gives permission.
+
+@item
+List on the Title Page, as authors, one or more persons or entities
+responsible for authorship of the modifications in the Modified
+Version, together with at least five of the principal authors of the
+Document (all of its principal authors, if it has fewer than five),
+unless they release you from this requirement.
+
+@item
+State on the Title page the name of the publisher of the
+Modified Version, as the publisher.
+
+@item
+Preserve all the copyright notices of the Document.
+
+@item
+Add an appropriate copyright notice for your modifications
+adjacent to the other copyright notices.
+
+@item
+Include, immediately after the copyright notices, a license notice
+giving the public permission to use the Modified Version under the
+terms of this License, in the form shown in the Addendum below.
+
+@item
+Preserve in that license notice the full lists of Invariant Sections
+and required Cover Texts given in the Document's license notice.
+
+@item
+Include an unaltered copy of this License.
+
+@item
+Preserve the section Entitled ``History'', Preserve its Title, and add
+to it an item stating at least the title, year, new authors, and
+publisher of the Modified Version as given on the Title Page. If
+there is no section Entitled ``History'' in the Document, create one
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+Version as stated in the previous sentence.
+
+@item
+Preserve the network location, if any, given in the Document for
+public access to a Transparent copy of the Document, and likewise
+the network locations given in the Document for previous versions
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+publisher of the version it refers to gives permission.
+
+@item
+For any section Entitled ``Acknowledgements'' or ``Dedications'', Preserve
+the Title of the section, and preserve in the section all the
+substance and tone of each of the contributor acknowledgements and/or
+dedications given therein.
+
+@item
+Preserve all the Invariant Sections of the Document,
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+or the equivalent are not considered part of the section titles.
+
+@item
+Delete any section Entitled ``Endorsements''. Such a section
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+
+@item
+Do not retitle any existing section to be Entitled ``Endorsements'' or
+to conflict in title with any Invariant Section.
+
+@item
+Preserve any Warranty Disclaimers.
+@end enumerate
+
+If the Modified Version includes new front-matter sections or
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+copied from the Document, you may at your option designate some or all
+of these sections as invariant. To do this, add their titles to the
+list of Invariant Sections in the Modified Version's license notice.
+These titles must be distinct from any other section titles.
+
+You may add a section Entitled ``Endorsements'', provided it contains
+nothing but endorsements of your Modified Version by various
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+been approved by an organization as the authoritative definition of a
+standard.
+
+You may add a passage of up to five words as a Front-Cover Text, and a
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+Front-Cover Text and one of Back-Cover Text may be added by (or
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+by arrangement made by the same entity you are acting on behalf of,
+you may not add another; but you may replace the old one, on explicit
+permission from the previous publisher that added the old one.
+
+The author(s) and publisher(s) of the Document do not by this License
+give permission to use their names for publicity for or to assert or
+imply endorsement of any Modified Version.
+
+@item
+COMBINING DOCUMENTS
+
+You may combine the Document with other documents released under this
+License, under the terms defined in section 4 above for modified
+versions, provided that you include in the combination all of the
+Invariant Sections of all of the original documents, unmodified, and
+list them all as Invariant Sections of your combined work in its
+license notice, and that you preserve all their Warranty Disclaimers.
+
+The combined work need only contain one copy of this License, and
+multiple identical Invariant Sections may be replaced with a single
+copy. If there are multiple Invariant Sections with the same name but
+different contents, make the title of each such section unique by
+adding at the end of it, in parentheses, the name of the original
+author or publisher of that section if known, or else a unique number.
+Make the same adjustment to the section titles in the list of
+Invariant Sections in the license notice of the combined work.
+
+In the combination, you must combine any sections Entitled ``History''
+in the various original documents, forming one section Entitled
+``History''; likewise combine any sections Entitled ``Acknowledgements'',
+and any sections Entitled ``Dedications''. You must delete all
+sections Entitled ``Endorsements.''
+
+@item
+COLLECTIONS OF DOCUMENTS
+
+You may make a collection consisting of the Document and other documents
+released under this License, and replace the individual copies of this
+License in the various documents with a single copy that is included in
+the collection, provided that you follow the rules of this License for
+verbatim copying of each of the documents in all other respects.
+
+You may extract a single document from such a collection, and distribute
+it individually under this License, provided you insert a copy of this
+License into the extracted document, and follow this License in all
+other respects regarding verbatim copying of that document.
+
+@item
+AGGREGATION WITH INDEPENDENT WORKS
+
+A compilation of the Document or its derivatives with other separate
+and independent documents or works, in or on a volume of a storage or
+distribution medium, is called an ``aggregate'' if the copyright
+resulting from the compilation is not used to limit the legal rights
+of the compilation's users beyond what the individual works permit.
+When the Document is included in an aggregate, this License does not
+apply to the other works in the aggregate which are not themselves
+derivative works of the Document.
+
+If the Cover Text requirement of section 3 is applicable to these
+copies of the Document, then if the Document is less than one half of
+the entire aggregate, the Document's Cover Texts may be placed on
+covers that bracket the Document within the aggregate, or the
+electronic equivalent of covers if the Document is in electronic form.
+Otherwise they must appear on printed covers that bracket the whole
+aggregate.
+
+@item
+TRANSLATION
+
+Translation is considered a kind of modification, so you may
+distribute translations of the Document under the terms of section 4.
+Replacing Invariant Sections with translations requires special
+permission from their copyright holders, but you may include
+translations of some or all Invariant Sections in addition to the
+original versions of these Invariant Sections. You may include a
+translation of this License, and all the license notices in the
+Document, and any Warranty Disclaimers, provided that you also include
+the original English version of this License and the original versions
+of those notices and disclaimers. In case of a disagreement between
+the translation and the original version of this License or a notice
+or disclaimer, the original version will prevail.
+
+If a section in the Document is Entitled ``Acknowledgements'',
+``Dedications'', or ``History'', the requirement (section 4) to Preserve
+its Title (section 1) will typically require changing the actual
+title.
+
+@item
+TERMINATION
+
+You may not copy, modify, sublicense, or distribute the Document
+except as expressly provided under this License. Any attempt
+otherwise to copy, modify, sublicense, or distribute it is void, and
+will automatically terminate your rights under this License.
+
+However, if you cease all violation of this License, then your license
+from a particular copyright holder is reinstated (a) provisionally,
+unless and until the copyright holder explicitly and finally
+terminates your license, and (b) permanently, if the copyright holder
+fails to notify you of the violation by some reasonable means prior to
+60 days after the cessation.
+
+Moreover, your license from a particular copyright holder is
+reinstated permanently if the copyright holder notifies you of the
+violation by some reasonable means, this is the first time you have
+received notice of violation of this License (for any work) from that
+copyright holder, and you cure the violation prior to 30 days after
+your receipt of the notice.
+
+Termination of your rights under this section does not terminate the
+licenses of parties who have received copies or rights from you under
+this License. If your rights have been terminated and not permanently
+reinstated, receipt of a copy of some or all of the same material does
+not give you any rights to use it.
+
+@item
+FUTURE REVISIONS OF THIS LICENSE
+
+The Free Software Foundation may publish new, revised versions
+of the GNU Free Documentation License from time to time. Such new
+versions will be similar in spirit to the present version, but may
+differ in detail to address new problems or concerns. See
+@uref{http://www.gnu.org/copyleft/}.
+
+Each version of the License is given a distinguishing version number.
+If the Document specifies that a particular numbered version of this
+License ``or any later version'' applies to it, you have the option of
+following the terms and conditions either of that specified version or
+of any later version that has been published (not as a draft) by the
+Free Software Foundation. If the Document does not specify a version
+number of this License, you may choose any version ever published (not
+as a draft) by the Free Software Foundation. If the Document
+specifies that a proxy can decide which future versions of this
+License can be used, that proxy's public statement of acceptance of a
+version permanently authorizes you to choose that version for the
+Document.
+
+@item
+RELICENSING
+
+``Massive Multiauthor Collaboration Site'' (or ``MMC Site'') means any
+World Wide Web server that publishes copyrightable works and also
+provides prominent facilities for anybody to edit those works. A
+public wiki that anybody can edit is an example of such a server. A
+``Massive Multiauthor Collaboration'' (or ``MMC'') contained in the
+site means any set of copyrightable works thus published on the MMC
+site.
+
+``CC-BY-SA'' means the Creative Commons Attribution-Share Alike 3.0
+license published by Creative Commons Corporation, a not-for-profit
+corporation with a principal place of business in San Francisco,
+California, as well as future copyleft versions of that license
+published by that same organization.
+
+``Incorporate'' means to publish or republish a Document, in whole or
+in part, as part of another Document.
+
+An MMC is ``eligible for relicensing'' if it is licensed under this
+License, and if all works that were first published under this License
+somewhere other than this MMC, and subsequently incorporated in whole
+or in part into the MMC, (1) had no cover texts or invariant sections,
+and (2) were thus incorporated prior to November 1, 2008.
+
+The operator of an MMC Site may republish an MMC contained in the site
+under CC-BY-SA on the same site at any time before August 1, 2009,
+provided the MMC is eligible for relicensing.
+
+@end enumerate
+
+@page
+@heading ADDENDUM: How to use this License for your documents
+
+To use this License in a document you have written, include a copy of
+the License in the document and put the following copyright and
+license notices just after the title page:
+
+@smallexample
+@group
+ Copyright (C) @var{year} @var{your name}.
+ Permission is granted to copy, distribute and/or modify this document
+ under the terms of the GNU Free Documentation License, Version 1.3
+ or any later version published by the Free Software Foundation;
+ with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
+ Texts. A copy of the license is included in the section entitled ``GNU
+ Free Documentation License''.
+@end group
+@end smallexample
+
+If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
+replace the ``with@dots{}Texts.''@: line with this:
+
+@smallexample
+@group
+ with the Invariant Sections being @var{list their titles}, with
+ the Front-Cover Texts being @var{list}, and with the Back-Cover Texts
+ being @var{list}.
+@end group
+@end smallexample
+
+If you have Invariant Sections without Cover Texts, or some other
+combination of the three, merge those two alternatives to suit the
+situation.
+
+If your document contains nontrivial examples of program code, we
+recommend releasing these examples in parallel under your choice of
+free software license, such as the GNU General Public License,
+to permit their use in free software.
+
+@c Local Variables:
+@c ispell-local-pdict: "ispell-dict"
+@c End:
diff --git a/doc/stamp-vti b/doc/stamp-vti
new file mode 100644
index 0000000..4f2a926
--- /dev/null
+++ b/doc/stamp-vti
@@ -0,0 +1,4 @@
+@set UPDATED 4 August 2016
+@set UPDATED-MONTH August 2016
+@set EDITION 3.5
+@set VERSION 3.5
diff --git a/doc/version.texi b/doc/version.texi
new file mode 100644
index 0000000..4f2a926
--- /dev/null
+++ b/doc/version.texi
@@ -0,0 +1,4 @@
+@set UPDATED 4 August 2016
+@set UPDATED-MONTH August 2016
+@set EDITION 3.5
+@set VERSION 3.5
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