Recently one of our web servers got screwed up by accidentally disabling the PHP module.
As far as our Nagios was concerned everything was fine, because the main web page still gave back a nice 200 OK
To add injury to insult, the page that were served were unparsed PHP files, including all kinds of sensitive information such as database logins, file locations etc.
So, not good.
I came up with this check in commands.cfg:
Then use this check for pages on your web server that you know should parse PHP. The arguments are the vhost name, and the URL: