adding build-aux/git-version-gen

[Jim Meyering]

I've been using this in coreutils for a few days, and like it:
[hmm... should have reloaded it to let the scriptversion update :-)

        * build-aux/git-version-gen: New file, from coreutils.  For details, see
        http://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=bfe49f506

Index: build-aux/git-version-gen
===================================================================
RCS file: build-aux/git-version-gen
diff -N build-aux/git-version-gen
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ build-aux/git-version-gen   2 Sep 2007 22:42:39 -0000
@@ -0,0 +1,83 @@
+#!/bin/sh
+# Print a version string.
+# This script is derived from GIT-VERSION-GEN from GIT: http://git.or.cz/.
+scriptversion=2007-06-30.12
+
+# Copyright (C) 2007 Free Software Foundation
+#
+# 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, 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, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301, USA.
+
+case $# in
+    2) ;;
+    *) echo 1>&2 "Usage: $0 \$VERSION \$srcdir/.version"; exit 1;;
+esac
+
+default_version=$1
+tarball_version_file=$2
+nl='
+'
+
+# First see if there is a tarball-only version file.
+# then try git-describe, then default.
+if test -f $tarball_version_file
+then
+    v=`cat $tarball_version_file` || exit 1
+    case $v in
+       *$nl*) v= ;; # reject multi-line output
+       [0-9]*) ;;
+       *) v= ;;
+    esac
+    test -z "$v" \
+       && echo "$0: WARNING: $tarball_version_file seems to be damaged" 1>&2
+fi
+
+if test -n "$v"
+then
+    : # use $v
+elif test -d .git \
+    && v=`git describe --abbrev=4 HEAD 2>/dev/null` \
+    && case $v in
+        v[0-9]*) ;;
+        *) (exit 1) ;;
+       esac
+then
+    # Remove the "g" in git-describe's output string; change each - to a '.'
+    v=`echo "$v" | sed 's/\(.*\)-g/\1-/;s/-/./g'`;
+else
+    v=$default_version
+fi
+
+v=`echo "$v" |sed 's/^v//'`
+
+dirty=`sh -c 'git diff-index --name-only HEAD' 2>/dev/null` || dirty=
+case "$dirty" in
+    '') ;;
+    *) # Append the suffix only if there isn't one already.
+       case $v in
+         *-dirty) ;;
+         *) v="$v-dirty" ;;
+       esac ;;
+esac
+
+# Omit the trailing newline, so that m4_esyscmd can use the result directly.
+echo "$v" | tr -d '\012'
+
+# Local variables:
+# eval: (add-hook 'write-file-hooks 'time-stamp)
+# time-stamp-start: "scriptversion="
+# time-stamp-format: "%:y-%02m-%02d.%02H"
+# time-stamp-end: "$"
+# End: