<p>Using vim 7.1, I recently heard you can debug php in VI.
But how?</p>

Put some content in the file /etc/issue
Some more details in
http://www.linuxfromscratch.org/blfs/view/svn/postlfs/logon.html
crap /etc/motd was the file i was trying to remember. Upvoting his answer :)