Modify documentation to note sed "-E" option, now in POSIX, for EREs.

2013-10-16  David A. Wheeler <dwheeler@dwheeler.com>

	* doc/sed-in.texi: Document "-E" option to use EREs.
	  GNU sed already supported "-E" as an undocumented synonym
	  for "-r", but "-E" is now in POSIX.
	  See: http://austingroupbugs.net/view.php?id=528.
	* doc/sed.1: Likewise.
	* doc/sed.texi: Likewise.
	* doc/sed.x: Likewise.
	* sed/sed.c: Likewise.

6 files changed, 49 insertions, 14 deletions

diff --git a/ChangeLog b/ChangeLog
index 4e1a0c2..da1d6fd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2013-10-16  David A. Wheeler <dwheeler@dwheeler.com>
+
+	* doc/sed-in.texi: Document "-E" option to use EREs.  GNU sed already
+	  supported "-E" as an undocumented synonym for "-r", but "-E" is now
+	  in POSIX.  See: http://austingroupbugs.net/view.php?id=528.
+	* doc/sed.1: Likewise.
+	* doc/sed.texi: Likewise.
+	* doc/sed.x: Likewise.
+	* sed/sed.c: Likewise.
+
 2013-10-06  Jose E. Marchesi  <jemarch@gnu.org>
 
 	* basicdefs.h (PATH_MAX): Defined to some constant in case it is
diff --git a/doc/sed-in.texi b/doc/sed-in.texi
index 40ba70b..1ed602f 100644
--- a/doc/sed-in.texi
+++ b/doc/sed-in.texi
@@ -318,8 +318,10 @@ follow the link and edit the ultimate destination of the
 link.  The default behavior is to break the symbolic link,
 so that the link destination will not be modified.
 
-@item -r
+@item -E
+@itemx -r
 @itemx --regexp-extended
+@opindex -E
 @opindex -r
 @opindex --regexp-extended
 @cindex Extended regular expressions, choosing
@@ -327,8 +329,15 @@ so that the link destination will not be modified.
 Use extended regular expressions rather than basic
 regular expressions.  Extended regexps are those that
 @command{egrep} accepts; they can be clearer because they
-usually have less backslashes, but are a @acronym{GNU} extension
-and hence scripts that use them are not portable.
+usually have fewer backslashes.
+Historically this was a @acronym{GNU} extension,
+but the @option{-E}
+extension has since been added to the POSIX standard
+(http://austingroupbugs.net/view.php?id=528),
+so use @option{-E} for portability.
+GNU sed has accepted @option{-E} as an undocumented option for years,
+and *BSD seds have accepted @option{-E} for years as well,
+but scripts that use @option{-E} might not port to other older systems.
 @xref{Extended regexps, , Extended regular expressions}.
 
 @ifset PERL
diff --git a/doc/sed.1 b/doc/sed.1
index 7acbcd0..2f02e64 100644
--- a/doc/sed.1
+++ b/doc/sed.1
@@ -1,5 +1,5 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.28.
-.TH SED "1" "February 2013" "sed 4.2.2" "User Commands"
+.TH SED "1" "October 2013" "sed 4.2.2" "User Commands"
 .SH NAME
 sed \- stream editor for filtering and transforming text
 .SH SYNOPSIS
@@ -48,9 +48,10 @@ specify the desired line-wrap length for the `l' command
 .IP
 disable all GNU extensions.
 .HP
-\fB\-r\fR, \fB\-\-regexp\-extended\fR
+\fB\-E\fR, \fB\-r\fR, \fB\-\-regexp\-extended\fR
 .IP
-use extended regular expressions in the script.
+use extended regular expressions in the script
+(for portability use POSIX \fB\-E\fR).
 .HP
 \fB\-s\fR, \fB\-\-separate\fR
 .IP
@@ -367,6 +368,9 @@ and similarly for
 .BR \ea ,
 .BR \et ,
 and other sequences.
+The \fI-E\fP option switches to using extended regular expressions instead;
+the -E option has been supported for years by GNU sed, and is now
+included in POSIX.
 .SH BUGS
 .PP
 E-mail bug reports to
diff --git a/doc/sed.texi b/doc/sed.texi
index 2bee542..a86ac6d 100644
--- a/doc/sed.texi
+++ b/doc/sed.texi
@@ -319,8 +319,10 @@ follow the link and edit the ultimate destination of the
 link.  The default behavior is to break the symbolic link,
 so that the link destination will not be modified.
 
-@item -r
+@item -E
+@itemx -r
 @itemx --regexp-extended
+@opindex -E
 @opindex -r
 @opindex --regexp-extended
 @cindex Extended regular expressions, choosing
@@ -328,8 +330,15 @@ so that the link destination will not be modified.
 Use extended regular expressions rather than basic
 regular expressions.  Extended regexps are those that
 @command{egrep} accepts; they can be clearer because they
-usually have less backslashes, but are a @acronym{GNU} extension
-and hence scripts that use them are not portable.
+usually have fewer backslashes.
+Historically this was a @acronym{GNU} extension,
+but the @option{-E}
+extension has since been added to the POSIX standard
+(http://austingroupbugs.net/view.php?id=528),
+so use @option{-E} for portability.
+GNU sed has accepted @option{-E} as an undocumented option for years,
+and *BSD seds have accepted @option{-E} for years as well,
+but scripts that use @option{-E} might not port to other older systems.
 @xref{Extended regexps, , Extended regular expressions}.
 
 @ifset PERL
@@ -814,7 +823,7 @@ operators.
 @item \@var{digit}
 Matches the @var{digit}-th @code{\(@dots{}\)} parenthesized
 subexpression in the regular expression.  This is called a @dfn{back
-reference}.  Subexpressions are implicitly numbered by counting
+reference}.  Subexpressions are implicity numbered by counting
 occurrences of @code{\(} left-to-right.
 
 @item \n
diff --git a/doc/sed.x b/doc/sed.x
index 433d52f..401bd88 100644
--- a/doc/sed.x
+++ b/doc/sed.x
@@ -4,7 +4,7 @@ sed \- a Stream EDitor
 .nf
 sed [-V] [--version] [--help] [-n] [--quiet] [--silent]
     [-l N] [--line-length=N] [-u] [--unbuffered]
-    [-r] [--regexp-extended] 
+    [-E] [-r] [--regexp-extended]
     [-e script] [--expression=script]
     [-f script-file] [--file=script-file]
     [script-if-no-other-script]
@@ -312,6 +312,9 @@ and similarly for
 .BR \ea ,
 .BR \et ,
 and other sequences.
+The \fI-E\fP option switches to using extended regular expressions instead;
+the -E option has been supported for years by GNU sed, and is now
+included in POSIX.
 
 [SEE ALSO]
 .BR awk (1),
diff --git a/sed/sed.c b/sed/sed.c
index af985e6..cff1505 100644
--- a/sed/sed.c
+++ b/sed/sed.c
@@ -125,8 +125,9 @@ Usage: %s [OPTION]... {script-only-if-no-other-script} [input-file]...\n\
                  specify the desired line-wrap length for the `l' command\n"));
   fprintf(out, _("  --posix\n\
                  disable all GNU extensions.\n"));
-  fprintf(out, _("  -r, --regexp-extended\n\
-                 use extended regular expressions in the script.\n"));
+  fprintf(out, _("  -E, -r, --regexp-extended\n\
+                 use extended regular expressions in the script\n\
+                 (for portability use POSIX -E).\n"));
 #ifdef REG_PERL
   fprintf(out, PERL_HELP);
 #endif
@@ -277,7 +278,6 @@ main(argc, argv)
 	  write_mode = "wb";
 	  break;
 
-	/* Undocumented, for compatibility with BSD sed.  */
 	case 'E':
 	case 'r':
 	  if (extended_regexp_flags)