backrenumber

#!/bin/bash
usage() { cat <<EOF
$*

Usage:
    backrenumber FILE [BACKUPS...]  # for bak in FILE~ FILE.~*~ BACKUPS...; do mv --backup=t bak FILE

BACKUPS: given args OR default are
    FILE.bak  FILE.bak~ FILE.bak.~*~
    FILE.orig FILE.orig~ FILE.orig.~*~
    FILE.save FILE.save~ FILE.save.~*~

Options:
    --help, -h, -?  show help
EOF
}
help_exit() {
	usage "backup renumber FILES."
	exit 0
}
error_exit() {
	usage $1 >&2
	exit 1
}
function pushback {
	local f
	for f in $@; do
		[ -f "$f" ] && back="$back $f" # append existing files to $back
	done
}
function pushbackt {
	local f
	for f in $@; do
		pushback $f{,~,.~*~} # fname fname~ fname.~*~
	done
}
# parse command line
case $1 in
--help|-h|-\?|"") help_exit;;
esac
file=$1
if [ ! -f "$file" ]; then
	error_exit "$file is not a file"
fi

# search backup files
pushback $file{~,.~*~}	# fname~ fname.~*~
if [ -n "$2" ]; then
	shift
	pushback "$@"
else
	pushbackt $file.bak	# fname.bak fname.bak~ fname.bak.~*~
	pushbackt $file.orig	# fname.orig fname.orig~ fname.orig.~*~
	pushbackt $file.save	# fname.save fname.save~ fname.save.~*~
fi
# print exist backup-files and do renumber
ls -tr1 $back | uniq
tmp=$(mktemp "$file.tmp.XXXXX")
mv $file $tmp
for bak in $(ls -tr1 $back $tmp | uniq); do
	mv --backup=t $bak $file
done