#!/bin/sh
: ${delay:=60}
while true; do
	for A; do
		case "$A" in
		*.bak | *.gz) continue ;;
		esac
		last=`echo "$A".*.bak`
		if [ -e "$last" ] && cmp "$A" "$last"; then
			:
		else
			if [ -e "$last" ]; then
				gzip "$last"
			fi
			cp -v "$A" "$A.`dt`.bak"
		fi
	done
	sleep "$delay"
done