watch a file for changes and log to logfile

watcher.sh

#!/bin/bash
while [ 1 ]; do
  before=`cat $1`
  sleep 1
  after=`cat $1`
  if [ "$before" != "$after" ]; then
    today=`date`
    echo "$1 changed on: $today" >> logfile.log
    echo "$1 changed on: $today and logged"
  fi
done