Unix is the preffered operating system of most Perlers, and here you will get to know as much as you can ever hope for in 20 minutes!
Introduction to UNIX for Web Developers
Covers essential commands as well as advanced tools.
Learn Unix by Example
Excellent guide for learning the Unix OS. Examples for many common tasks.
UNIX-Getting Your Feet Wet
Good basic introduction, contains some information specific to the University of Chicago.