in reply to Build in modules in perl

To get a quick overview of the modules used by the current package, try Module::Used which has a bin script modules-used included with it. Simply do for example CGI:
modules-used source-file /usr/lib/perl5/5.8.8/CGI.pm
Just make sure that you give the full path to your module, script, file, or source, and you're good to go.