build: update bootstrap and tests/init.sh from gnulib

* bootstrap: Update from gnulib.
* tests/init.sh: Likewise.

2 files changed, 212 insertions, 99 deletions

diff --git a/bootstrap b/bootstrap
index f3e3be2..f76db9a 100755
--- a/bootstrap
+++ b/bootstrap
@@ -1,6 +1,6 @@
 #! /bin/sh
 # Print a version string.
-scriptversion=2010-07-06.10; # UTC
+scriptversion=2011-08-11.17; # UTC
 
 # Bootstrap this package from checked-out sources.
 
@@ -42,24 +42,32 @@ local_gl_dir=gl
 bt='._bootmp'
 bt_regex=`echo "$bt"| sed 's/\./[.]/g'`
 bt2=${bt}2
+me=$0
 
 usage() {
   cat <<EOF
-Usage: $0 [OPTION]...
+Usage: $me [OPTION]...
 Bootstrap this package from the checked-out sources.
 
 Options:
- --gnulib-srcdir=DIRNAME  Specify the local directory where gnulib
+ --gnulib-srcdir=DIRNAME  specify the local directory where gnulib
                           sources reside.  Use this if you already
                           have gnulib sources on your machine, and
                           do not want to waste your bandwidth downloading
-                          them again.  Defaults to \$GNULIB_SRCDIR.
- --copy                   Copy files instead of creating symbolic links.
- --force                  Attempt to bootstrap even if the sources seem
-                          not to have been checked out.
- --skip-po                Do not download po files.
-
-If the file $0.conf exists in the same directory as this script, its
+                          them again.  Defaults to \$GNULIB_SRCDIR
+ --bootstrap-sync         if this bootstrap script is not identical to
+                          the version in the local gnulib sources,
+                          update this script, and then restart it with
+                          /bin/sh or the shell \$CONFIG_SHELL
+ --no-bootstrap-sync      do not check whether bootstrap is out of sync
+ --copy                   copy files instead of creating symbolic links
+ --force                  attempt to bootstrap even if the sources seem
+                          not to have been checked out
+ --no-git                 do not use git to update gnulib.  Requires that
+                          --gnulib-srcdir point to a correct gnulib snapshot
+ --skip-po                do not download po files
+
+If the file $me.conf exists in the same directory as this script, its
 contents are read as shell variables to configure the bootstrap.
 
 For build prerequisites, environment variables like \$AUTOCONF and \$AMTAR
@@ -80,6 +88,10 @@ gnulib_modules=
 # Any gnulib files needed that are not in modules.
 gnulib_files=
 
+# A function to be called to edit gnulib.mk right after it's created.
+# Override it via your own definition in bootstrap.conf.
+gnulib_mk_hook() { :; }
+
 # A function to be called after everything else in this script.
 # Override it via your own definition in bootstrap.conf.
 bootstrap_epilogue() { :; }
@@ -118,18 +130,7 @@ source_base=lib
 m4_base=m4
 doc_base=doc
 tests_base=tests
-
-# Extra files from gnulib, which override files from other sources.
-gnulib_extra_files="
-        $build_aux/install-sh
-        $build_aux/missing
-        $build_aux/mdate-sh
-        $build_aux/texinfo.tex
-        $build_aux/depcomp
-        $build_aux/config.guess
-        $build_aux/config.sub
-        doc/INSTALL
-"
+gnulib_extra_files=''
 
 # Additional gnulib-tool options to use.  Use "\newline" to break lines.
 gnulib_tool_option_extras=
@@ -164,6 +165,13 @@ copy=false
 # on which version control system (if any) is used in the source directory.
 vc_ignore=auto
 
+# Set this to true in bootstrap.conf to enable --bootstrap-sync by
+# default.
+bootstrap_sync=false
+
+# Use git to update gnulib sources
+use_git=true
+
 # find_tool ENVVAR NAMES...
 # -------------------------
 # Search for a required program.  Use the value of ENVVAR, if set,
@@ -188,11 +196,11 @@ find_tool ()
     find_tool_error_prefix="\$$find_tool_envvar: "
   fi
   if test x"$find_tool_res" = x; then
-    echo >&2 "$0: one of these is required: $find_tool_names"
+    echo >&2 "$me: one of these is required: $find_tool_names"
     exit 1
   fi
   ($find_tool_res --version </dev/null) >/dev/null 2>&1 || {
-    echo >&2 "$0: ${find_tool_error_prefix}cannot run $find_tool_res --version"
+    echo >&2 "$me: ${find_tool_error_prefix}cannot run $find_tool_res --version"
     exit 1
   }
   eval "$find_tool_envvar=\$find_tool_res"
@@ -210,6 +218,18 @@ case "$0" in
   *) test -r "$0.conf" && . ./"$0.conf" ;;
 esac
 
+# Extra files from gnulib, which override files from other sources.
+test -z "${gnulib_extra_files}" && \
+  gnulib_extra_files="
+        $build_aux/install-sh
+        $build_aux/missing
+        $build_aux/mdate-sh
+        $build_aux/texinfo.tex
+        $build_aux/depcomp
+        $build_aux/config.guess
+        $build_aux/config.sub
+        doc/INSTALL
+"
 
 if test "$vc_ignore" = auto; then
   vc_ignore=
@@ -235,28 +255,71 @@ do
     checkout_only_file=;;
   --copy)
     copy=true;;
+  --bootstrap-sync)
+    bootstrap_sync=true;;
+  --no-bootstrap-sync)
+    bootstrap_sync=false;;
+  --no-git)
+    use_git=false;;
   *)
     echo >&2 "$0: $option: unknown option"
     exit 1;;
   esac
 done
 
+if $use_git || test -d "$GNULIB_SRCDIR"; then
+  :
+else
+  echo "$0: Error: --no-git requires --gnulib-srcdir" >&2
+  exit 1
+fi
+
 if test -n "$checkout_only_file" && test ! -r "$checkout_only_file"; then
   echo "$0: Bootstrapping from a non-checked-out distribution is risky." >&2
   exit 1
 fi
 
+# Ensure that lines starting with ! sort last, per gitignore conventions
+# for whitelisting exceptions after a more generic blacklist pattern.
+sort_patterns() {
+  sort -u "$@" | sed '/^!/ {
+    H
+    d
+  }
+  $ {
+    P
+    x
+    s/^\n//
+  }' | sed '/^$/d'
+}
+
 # If $STR is not already on a line by itself in $FILE, insert it,
 # sorting the new contents of the file and replacing $FILE with the result.
 insert_sorted_if_absent() {
   file=$1
   str=$2
   test -f $file || touch $file
-  echo "$str" | sort -u - $file | cmp - $file > /dev/null \
-    || echo "$str" | sort -u - $file -o $file \
+  echo "$str" | sort_patterns - $file | cmp - $file > /dev/null \
+    || { echo "$str" | sort_patterns - $file > $file.bak \
+      && mv $file.bak $file; } \
     || exit 1
 }
 
+# Adjust $PATTERN for $VC_IGNORE_FILE and insert it with
+# insert_sorted_if_absent.
+insert_vc_ignore() {
+  vc_ignore_file="$1"
+  pattern="$2"
+  case $vc_ignore_file in
+  *.gitignore)
+    # A .gitignore entry that does not start with `/' applies
+    # recursively to subdirectories, so prepend `/' to every
+    # .gitignore entry.
+    pattern=`echo "$pattern" | sed s,^,/,`;;
+  esac
+  insert_sorted_if_absent "$vc_ignore_file" "$pattern"
+}
+
 # Die if there is no AC_CONFIG_AUX_DIR($build_aux) line in configure.ac.
 found_aux_dir=no
 grep '^[	 ]*AC_CONFIG_AUX_DIR(\['"$build_aux"'\])' configure.ac \
@@ -275,7 +338,7 @@ if test ! -d $build_aux; then
   mkdir $build_aux
   for dot_ig in x $vc_ignore; do
     test $dot_ig = x && continue
-    insert_sorted_if_absent $dot_ig $build_aux
+    insert_vc_ignore $dot_ig $build_aux
   done
 fi
 
@@ -325,17 +388,18 @@ get_version() {
   $app --version >/dev/null 2>&1 || return 1
 
   $app --version 2>&1 |
-  sed -n '# extract version within line
-          s/.*[v ]\{1,\}\([0-9]\{1,\}\.[.a-z0-9-]*\).*/\1/
-          t done
+  sed -n '# Move version to start of line.
+          s/.*[v ]\([0-9]\)/\1/
+
+          # Skip lines that do not start with version.
+          /^[0-9]/!d
 
-          # extract version at start of line
-          s/^\([0-9]\{1,\}\.[.a-z0-9-]*\).*/\1/
-          t done
+          # Remove characters after the version.
+          s/[^.a-z0-9-].*//
 
-          d
+          # The first component must be digits only.
+          s/^\([0-9]*\)[a-z-].*/\1/
 
-          :done
           #the following essentially does s/5.005/5.5/
           s/\.0*\([1-9]\)/.\1/g
           p
@@ -346,21 +410,43 @@ check_versions() {
   ret=0
 
   while read app req_ver; do
+    # We only need libtoolize from the libtool package.
+    if test "$app" = libtool; then
+      app=libtoolize
+    fi
+    # Exempt git if --no-git is in effect.
+    if test "$app" = git; then
+      $use_git || continue
+    fi
     # Honor $APP variables ($TAR, $AUTOCONF, etc.)
-    appvar=`echo $app | tr '[a-z]' '[A-Z]'`
+    appvar=`echo $app | tr '[a-z]-' '[A-Z]_'`
     test "$appvar" = TAR && appvar=AMTAR
-    eval "app=\${$appvar-$app}"
-    inst_ver=$(get_version $app)
-    if [ ! "$inst_ver" ]; then
-      echo "Error: '$app' not found" >&2
-      ret=1
-    elif [ ! "$req_ver" = "-" ]; then
-      latest_ver=$(sort_ver $req_ver $inst_ver | cut -d' ' -f2)
-      if [ ! "$latest_ver" = "$inst_ver" ]; then
-        echo "Error: '$app' version == $inst_ver is too old" >&2
-        echo "       '$app' version >= $req_ver is required" >&2
+    case $appvar in
+        GZIP) ;; # Do not use $GZIP:  it contains gzip options.
+        *) eval "app=\${$appvar-$app}" ;;
+    esac
+    if [ "$req_ver" = "-" ]; then
+      # Merely require app to exist; not all prereq apps are well-behaved
+      # so we have to rely on $? rather than get_version.
+      $app --version >/dev/null 2>&1
+      if [ 126 -le $? ]; then
+        echo "$me: Error: '$app' not found" >&2
         ret=1
       fi
+    else
+      # Require app to produce a new enough version string.
+      inst_ver=$(get_version $app)
+      if [ ! "$inst_ver" ]; then
+        echo "$me: Error: '$app' not found" >&2
+        ret=1
+      else
+        latest_ver=$(sort_ver $req_ver $inst_ver | cut -d' ' -f2)
+        if [ ! "$latest_ver" = "$inst_ver" ]; then
+          echo "$me: Error: '$app' version == $inst_ver is too old" >&2
+          echo "       '$app' version >= $req_ver is required" >&2
+          ret=1
+        fi
+      fi
     fi
   done
 
@@ -370,16 +456,30 @@ check_versions() {
 print_versions() {
   echo "Program    Min_version"
   echo "----------------------"
-  printf "$buildreq"
+  printf %s "$buildreq"
   echo "----------------------"
   # can't depend on column -t
 }
 
+use_libtool=0
+# We'd like to use grep -E, to see if any of LT_INIT,
+# AC_PROG_LIBTOOL, AM_PROG_LIBTOOL is used in configure.ac,
+# but that's not portable enough (e.g., for Solaris).
+grep '^[	 ]*A[CM]_PROG_LIBTOOL' configure.ac >/dev/null \
+  && use_libtool=1
+grep '^[	 ]*LT_INIT' configure.ac >/dev/null \
+  && use_libtool=1
+if test $use_libtool = 1; then
+  find_tool LIBTOOLIZE glibtoolize libtoolize
+fi
+
 if ! printf "$buildreq" | check_versions; then
-  test -f README-prereq &&
-  echo "See README-prereq for notes on obtaining these prerequisite programs:" >&2
-  echo
-  print_versions
+  echo >&2
+  if test -f README-prereq; then
+    echo "$0: See README-prereq for how to get the prerequisite programs" >&2
+  else
+    echo "$0: Please install the prerequisite programs" >&2
+  fi
   exit 1
 fi
 
@@ -390,11 +490,11 @@ if test -d .git && (git --version) >/dev/null 2>/dev/null ; then
   if git config merge.merge-changelog.driver >/dev/null ; then
     :
   elif (git-merge-changelog --version) >/dev/null 2>/dev/null ; then
-    echo "initializing git-merge-changelog driver"
+    echo "$0: initializing git-merge-changelog driver"
     git config merge.merge-changelog.name 'GNU-style ChangeLog merge driver'
     git config merge.merge-changelog.driver 'git-merge-changelog %O %A %B'
   else
-    echo "consider installing git-merge-changelog from gnulib"
+    echo "$0: consider installing git-merge-changelog from gnulib"
   fi
 fi
 
@@ -410,7 +510,7 @@ git_modules_config () {
 }
 
 gnulib_path=`git_modules_config submodule.gnulib.path`
-: ${gnulib_path=gnulib}
+test -z "$gnulib_path" && gnulib_path=gnulib
 
 # Get gnulib files.
 
@@ -463,6 +563,16 @@ case ${GNULIB_SRCDIR--} in
   ;;
 esac
 
+if $bootstrap_sync; then
+  cmp -s "$0" "$GNULIB_SRCDIR/build-aux/bootstrap" || {
+    echo "$0: updating bootstrap and restarting..."
+    exec sh -c \
+      'cp "$1" "$2" && shift && exec "${CONFIG_SHELL-/bin/sh}" "$@"' \
+      -- "$GNULIB_SRCDIR/build-aux/bootstrap" \
+      "$0" "$@" --no-bootstrap-sync
+  }
+fi
+
 gnulib_tool=$GNULIB_SRCDIR/gnulib-tool
 <$gnulib_tool || exit
 
@@ -471,7 +581,7 @@ gnulib_tool=$GNULIB_SRCDIR/gnulib-tool
 download_po_files() {
   subdir=$1
   domain=$2
-  echo "$0: getting translations into $subdir for $domain..."
+  echo "$me: getting translations into $subdir for $domain..."
   cmd=`printf "$po_download_command_format" "$domain" "$subdir"`
   eval "$cmd"
 }
@@ -505,7 +615,7 @@ update_po_files() {
         ! test -f "$po_dir/$po.po" ||
         ! $SHA1SUM -c --status "$cksum_file" \
             < "$new_po" > /dev/null; then
-      echo "updated $po_dir/$po.po..."
+      echo "$me: updated $po_dir/$po.po..."
       cp "$new_po" "$po_dir/$po.po" \
           && $SHA1SUM < "$new_po" > "$cksum_file"
     fi
@@ -543,34 +653,42 @@ symlink_to_dir()
       for dot_ig in x $vc_ignore; do
         test $dot_ig = x && continue
         ig=$parent/$dot_ig
-        insert_sorted_if_absent $ig `echo "$dst_dir"|sed 's,.*/,,'`
+        insert_vc_ignore $ig `echo "$dst_dir"|sed 's,.*/,,'`
       done
     fi
 
     if $copy; then
       {
         test ! -h "$dst" || {
-          echo "$0: rm -f $dst" &&
+          echo "$me: rm -f $dst" &&
           rm -f "$dst"
         }
       } &&
       test -f "$dst" &&
       cmp -s "$src" "$dst" || {
-        echo "$0: cp -fp $src $dst" &&
+        echo "$me: cp -fp $src $dst" &&
         cp -fp "$src" "$dst"
       }
     else
+      # Leave any existing symlink alone, if it already points to the source,
+      # so that broken build tools that care about symlink times
+      # aren't confused into doing unnecessary builds.  Conversely, if the
+      # existing symlink's time stamp is older than the source, make it afresh,
+      # so that broken tools aren't confused into skipping needed builds.  See
+      # <http://lists.gnu.org/archive/html/bug-gnulib/2011-05/msg00326.html>.
       test -h "$dst" &&
       src_ls=`ls -diL "$src" 2>/dev/null` && set $src_ls && src_i=$1 &&
       dst_ls=`ls -diL "$dst" 2>/dev/null` && set $dst_ls && dst_i=$1 &&
-      test "$src_i" = "$dst_i" || {
+      test "$src_i" = "$dst_i" &&
+      both_ls=`ls -dt "$src" "$dst"` &&
+      test "X$both_ls" = "X$dst$nl$src" || {
         dot_dots=
         case $src in
         /*) ;;
         *)
           case /$dst/ in
           *//* | */../* | */./* | /*/*/*/*/*/)
-             echo >&2 "$0: invalid symlink calculation: $src -> $dst"
+             echo >&2 "$me: invalid symlink calculation: $src -> $dst"
              exit 1;;
           /*/*/*/*/)	dot_dots=../../../;;
           /*/*/*/)	dot_dots=../../;;
@@ -578,7 +696,7 @@ symlink_to_dir()
           esac;;
         esac
 
-        echo "$0: ln -fs $dot_dots$src $dst" &&
+        echo "$me: ln -fs $dot_dots$src $dst" &&
         ln -fs "$dot_dots$src" "$dst"
       }
     fi
@@ -611,7 +729,7 @@ cp_mark_as_generated()
       cmp -s "$cp_src" "$cp_dst" || {
         # Copy the file first to get proper permissions if it
         # doesn't already exist.  Then overwrite the copy.
-        echo "$0: cp -f $cp_src $cp_dst" &&
+        echo "$me: cp -f $cp_src $cp_dst" &&
         rm -f "$cp_dst" &&
         cp "$cp_src" "$cp_dst-t" &&
         sed "s!$bt_regex/!!g" "$cp_src" > "$cp_dst-t" &&
@@ -629,7 +747,7 @@ cp_mark_as_generated()
       if cmp -s "$cp_dst-t" "$cp_dst"; then
         rm -f "$cp_dst-t"
       else
-        echo "$0: cp $cp_src $cp_dst # with edits" &&
+        echo "$me: cp $cp_src $cp_dst # with edits" &&
         mv -f "$cp_dst-t" "$cp_dst"
       fi
     fi
@@ -648,7 +766,7 @@ version_controlled_file() {
   elif test -d .svn; then
     svn log -r HEAD "$dir/$file" > /dev/null 2>&1 && found=yes
   else
-    echo "$0: no version control for $dir/$file?" >&2
+    echo "$me: no version control for $dir/$file?" >&2
   fi
   test $found = yes
 }
@@ -660,7 +778,8 @@ slurp() {
     for file in `ls -a $1/$dir`; do
       case $file in
       .|..) continue;;
-      .*) continue;; # FIXME: should all file names starting with "." be ignored?
+      # FIXME: should all file names starting with "." be ignored?
+      .*) continue;;
       esac
       test -d $1/$dir/$file && continue
       for excluded_file in $excluded_files; do
@@ -669,30 +788,19 @@ slurp() {
       if test $file = Makefile.am && test "X$gnulib_mk" != XMakefile.am; then
         copied=$copied${sep}$gnulib_mk; sep=$nl
         remove_intl='/^[^#].*\/intl/s/^/#/;'"s!$bt_regex/!!g"
-        sed "$remove_intl" $1/$dir/$file | cmp - $dir/$gnulib_mk > /dev/null || {
-          echo "$0: Copying $1/$dir/$file to $dir/$gnulib_mk ..." &&
+        sed "$remove_intl" $1/$dir/$file |
+        cmp - $dir/$gnulib_mk > /dev/null || {
+          echo "$me: Copying $1/$dir/$file to $dir/$gnulib_mk ..." &&
           rm -f $dir/$gnulib_mk &&
-          sed "$remove_intl" $1/$dir/$file >$dir/$gnulib_mk
+          sed "$remove_intl" $1/$dir/$file >$dir/$gnulib_mk &&
+          gnulib_mk_hook $dir/$gnulib_mk
         }
       elif { test "${2+set}" = set && test -r $2/$dir/$file; } ||
            version_controlled_file $dir $file; then
-        echo "$0: $dir/$file overrides $1/$dir/$file"
+        echo "$me: $dir/$file overrides $1/$dir/$file"
       else
         copied=$copied$sep$file; sep=$nl
-        if test $file = gettext.m4; then
-          echo "$0: patching m4/gettext.m4 to remove need for intl/* ..."
-          rm -f $dir/$file
-          sed '
-            /^AC_DEFUN(\[AM_INTL_SUBDIR],/,/^]/c\
-              AC_DEFUN([AM_INTL_SUBDIR], [])
-            /^AC_DEFUN(\[gt_INTL_SUBDIR_CORE],/,/^]/c\
-              AC_DEFUN([gt_INTL_SUBDIR_CORE], [])
-            $a\
-              AC_DEFUN([gl_LOCK_EARLY], [])
-          ' $1/$dir/$file >$dir/$file
-        else
-          cp_mark_as_generated $1/$dir/$file $dir/$file
-        fi
+        cp_mark_as_generated $1/$dir/$file $dir/$file
       fi || exit
     done
 
@@ -700,18 +808,25 @@ slurp() {
       test $dot_ig = x && continue
       ig=$dir/$dot_ig
       if test -n "$copied"; then
-        insert_sorted_if_absent $ig "$copied"
+        insert_vc_ignore $ig "$copied"
         # If an ignored file name ends with .in.h, then also add
         # the name with just ".h".  Many gnulib headers are generated,
         # e.g., stdint.in.h -> stdint.h, dirent.in.h ->..., etc.
         # Likewise for .gperf -> .h, .y -> .c, and .sin -> .sed
-        f=`echo "$copied"|sed 's/\.in\.h$/.h/;s/\.sin$/.sed/;s/\.y$/.c/;s/\.gperf$/.h/'`
-        insert_sorted_if_absent $ig "$f"
+        f=`echo "$copied" |
+          sed '
+            s/\.in\.h$/.h/
+            s/\.sin$/.sed/
+            s/\.y$/.c/
+            s/\.gperf$/.h/
+          '
+        `
+        insert_vc_ignore $ig "$f"
 
         # For files like sys_stat.in.h and sys_time.in.h, record as
         # ignorable the directory we might eventually create: sys/.
         f=`echo "$copied"|sed 's/sys_.*\.in\.h$/sys/'`
-        insert_sorted_if_absent $ig "$f"
+        insert_vc_ignore $ig "$f"
       fi
     done
   done
@@ -736,6 +851,12 @@ gnulib_tool_options="\
  --local-dir $local_gl_dir\
  $gnulib_tool_option_extras\
 "
+if test $use_libtool = 1; then
+  case "$gnulib_tool_options " in
+    *' --libtool '*) ;;
+    *) gnulib_tool_options="$gnulib_tool_options --libtool" ;;
+  esac
+fi
 echo "$0: $gnulib_tool $gnulib_tool_options --import ..."
 $gnulib_tool $gnulib_tool_options --import $gnulib_modules &&
 slurp $bt || exit
@@ -778,26 +899,18 @@ grep -E '^[	 ]*AC_CONFIG_HEADERS?\>' configure.ac >/dev/null ||
 
 for command in \
   libtool \
-  "${ACLOCAL-aclocal} --force -I m4" \
+  "${ACLOCAL-aclocal} --force -I '$m4_base' $ACLOCAL_FLAGS" \
   "${AUTOCONF-autoconf} --force" \
   "${AUTOHEADER-autoheader} --force" \
   "${AUTOMAKE-automake} --add-missing --copy --force-missing"
 do
   if test "$command" = libtool; then
-    use_libtool=0
-    # We'd like to use grep -E, to see if any of LT_INIT,
-    # AC_PROG_LIBTOOL, AM_PROG_LIBTOOL is used in configure.ac,
-    # but that's not portable enough (e.g., for Solaris).
-    grep '^[	 ]*A[CM]_PROG_LIBTOOL' configure.ac >/dev/null \
-      && use_libtool=1
-    grep '^[	 ]*LT_INIT' configure.ac >/dev/null \
-      && use_libtool=1
     test $use_libtool = 0 \
       && continue
     command="${LIBTOOLIZE-libtoolize} -c -f"
   fi
   echo "$0: $command ..."
-  $command || exit
+  eval "$command" || exit
 done
 
 
diff --git a/tests/init.sh b/tests/init.sh
index 0da6c1e..d3fb28c 100644
--- a/tests/init.sh
+++ b/tests/init.sh
@@ -208,7 +208,7 @@ export MALLOC_PERTURB_
 # a partition, or to undo any other global state changes.
 cleanup_ () { :; }
 
-if ( diff --version < /dev/null 2>&1 | grep GNU ) > /dev/null 2>&1; then
+if ( diff -u "$0" "$0" < /dev/null ) > /dev/null 2>&1; then
   compare () { diff -u "$@"; }
 elif ( cmp --version < /dev/null 2>&1 | grep GNU ) > /dev/null 2>&1; then
   compare () { cmp -s "$@"; }