Possibly the best referencing book for UNIX! The book covers from simple to advanced concepts with easy-to-understand examples.

This is an awesome book I love it! I bought it used but I am going to have to buy it to get the software..
Its hard be patient, wade through it and try everything outRight now I am using it as a textbook for a class I am taking but I will always treasure it and I cannot wait to read the new edition if there is one!! 

If you want to know the nitty-gritty detail and hack of the "usage" of Unix commands, short cuts, then this must be a very good book. This is the first book I read when I learn Unix in my COMP111 course :)
Reading this books really needs times, if you want a very quick start, you'd better find another crash course books. However, if you decide want to be an expert in Unix or want a reference book, then this is one of the best book in Unix (or says Linux).  

Review: UNIX Power Tools

There is always a new trick you can learn from this book once you open a random page. This is one of the books that I always keep around and even keep an ebook version on my ipod. One of the best Unix related books I've ever seen. Read full review

Review: UNIX Power Tools

practical, useful. i keep coming back to it. it's a serious general reference tool for anything unix related. it's a great introduction to a serious beginner. worth every penny, especially if purchased used ;) be sure to get the latest edition as it computing technology changes rapidly. Read full review

Review: UNIX Power Tools

Must have if you're looking to use a Unix based system. Includes tutorials, tips, and cookbook style tidbits to get you through some difficult task on the Unix command line. Should be on every serious *Nixers reference shelf. Read full review