UNIX For Dummies Guide!
 

Adrian's Rojak Pot Posts Unix Guide

To many people, UNIX is an old, kludgy operating system. However,
the truth is the UNIX operating system is still alive an well. In fact, it
forms the foundation of many mainstream operating systems like Linux, Mac OS
X, Solaris and FreeBSD!

Unix has been and still is very much a part of the infrastructure of the web and operating systems for many serious companies.

You can read the guide here.