#!/bin/rc -e
# Usage: $0 <paths> -- <cmd>

paths=()
while(! ~ $#* 0 && ! ~ $1 --) {
	paths=($paths $1)
	shift
}
shift
cmd=$*

if(~ $#paths 0 || ~ $#cmd 0) {
	echo Usage: $0 '<paths> -- <cmd>' >[1=2]
	exit badargs
}

oldsum=''
while() {
	newsum=`{walk -f $paths | xargs cat | sum | awk '{print $1}'}
	if(! ~ $newsum $oldsum) {
		oldsum=$newsum
		echo '####' `{date | awk '{print $4}'} $cmd
		eval $cmd
	}
	sleep 2
}