Just want to add this link to your already great tutorial:

How2 create a PPM distribution by Jan Krynicky.

Update: changed from "Just want to add a link to this already great tutorial" which was not clear

Simon Flack ($code or die)
$,=reverse'"ro_';s,$,\$,;s,$,lc ref sub{},e;$,
=~y'_"' ';eval"die";print $_,lc substr$@,0,3;