For more information visit Perl.org and CPAN . There are lots of books about Perl. Standard works include Learning Perl, Programming Perl (the bible), Perl Cookbook , and Advanced Perl Programming. For everything about regular expressions read Mastering Regular Expressions.
Finally, I've written lots of Perl code over the past few years (around 40,000 lines at the last count), for system programming, XML processing, and PCS configuration. For example, this document was written in XML and processed by my Perl XML toolchain. All this code is available for reference, and for use where it fits.
John Storrs