#!/bin/bash
# https://svn.bdgn.net/public/test/bekir/bin/diffintime

INTERVAL=1

if [ "$1" = "-n" ] ; then
    INTERVAL=$2
    shift 2
fi

COMMAND="$@"
NEW=$(mktemp /tmp/diffintime.XXXXXXXXXX)
OLD=$(mktemp /tmp/diffintime.XXXXXXXXXX)

trap "rm $NEW $OLD; echo; exit 1" SIGTERM SIGINT

while /bin/true; do
    test -f $NEW && mv $NEW $OLD
    bash -c "$COMMAND" &> $NEW
    diff=$(diff $OLD $NEW |grep -v -- --- | grep -v "^[0-9,]\+[acd][0-9,]\+$")
    test -n "$diff" && date +%Y-%m-%d\ %H:%M:%S && echo "$diff"
    sleep $INTERVAL
done

rm $NEW $OLD
exit 0