You could go even further and take a look at Perl Power Tools.

Well, ppt used to be cool, but the project seems to be sleeping now... and anyway the purpose here is not to show how to reimplement possibly complex *NIX commands in Perl, but just the reverse: to show how things a newbie may want to system (or similar) out to an external program to do can be handled just fine with basic perl construct or judicious use of a core or CPAN module.