Ditto. Learning Perl by Randal Schwartz. And the great thing is that Randal sometimes hangs out here on this forum using the name 'Merlyn'. So if you don't understand something ask a question and the author of the book itself just might answer you.

I have found Merlyn's chapter on formats is more complete and easier to understand than the way the other Perl canonical text (Programming Perl, aka Camel) presents the info. He also has a complete chapter on CGI.pm, which every new Perl programmer ought to know about.

The above remarks refer to the second edition of Learning Perl. A third edition is in the process of coming out.