page_monitor.sh

page_monitor.sh

#!/usr/bin/env bash

# Super quick-n-dirty, cronable bash script to monitor webpage changes and notify via email

# Discussion:
# For every site, sanity check this whole script by running it twice while the page hasn't changed.
# (Due to md5 hashing, this script won't work with any site that serves up a dynamic content body.)
#
# The host must be able to send email via `mail`.
# I used this guide to get up and running in ~5 minutes:
# http://library.linode.com/email/exim/send-only-mta-debian-6-squeeze


url="http://foo.com/bar"
emailAddress="1234567890@txt.att.net"   # trick to support cell phone updates!
hashFile="/home/josh/pagecheck_mt.md5"

currentMD5=$(wget -q -O - $url | md5sum | cut -d ' ' -f 1)

if [ -f $hashFile ];
then
  previousMD5=$(cat $hashFile | cut -d ' ' -f 1)

  if [ "$currentMD5" != "$previousMD5" ];
  then
    mail -s "UPDATED: $url" $emailAddress < /dev/null 2> /dev/null
  fi
fi

echo $currentMD5 > $hashFile

Set up a cronjob like so, to check for page changes every minute:

* * * * * /foo/bar/page_monitor.sh &> /dev/null