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|
#!/bin/sh
# usage: ifchange target temporary
set -e
timestamp=
keepsuffix=
empty=
until [ $# -eq 0 ]; do
case "$1" in
--timestamp)
timestamp=.
;;
--timestamp=*)
timestamp=`expr \( "$1" : '[^=]*=\(.*\)' \)`
;;
--keep)
keepsuffix=.old
;;
--keep=*)
keepsuffix=`expr \( "$1" : '[^=]*=\(.*\)' \)`
;;
--empty)
empty=yes
;;
*)
break
;;
esac
shift
done
target="$1"
temp="$2"
if [ "$temp" = - ]; then
temp="tmpdata$$.tmp~"
cat > "$temp" || exit $?
trap 'rm -f "$temp"' 0
fi
if [ -f "$target" -a ! -${empty:+f}${empty:-s} "$temp" ] || cmp "$target" "$temp" >/dev/null 2>&1; then
echo "$target unchanged"
rm -f "$temp"
else
echo "$target updated"
[ x"${keepsuffix}" = x ] || mv -f "$target" "${target}${keepsuffix}"
mv -f "$temp" "$target"
fi
if [ -n "${timestamp}" ]; then
if [ x"${timestamp}" = x. ]; then
case "$target" in
*/*)
timestamp=`dirname "$target"`/.time.`basename "$target"`
;;
*)
timestamp=.time."$target"
;;
esac
fi
: > "$timestamp"
fi
|
