If you like the Dummies books, the best of this series' Linux books remains "Advanced Programming in the UNIX® Environment". It was released in 2005, and is an update of the classic first edition (released in 1992) by the late W. Richard Stevens.
http://www.apuebook.com/[
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The "Advanced Linux Programming" is freely available and is an excellent book on Linux system programming.
http://www.advancedlinuxprogramming.com/[
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The classic guide to UNIX(R) programming of Marc J. Rochkind !
The book "Advanced UNIX Programming" is still used and considered to be a must have book on any UNIX programmer's shelf.
http://www.amazon.com/Advanced-UNIX-Programming-2nd-Edition/dp/0131411543[
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No matter what book you get though, the absolute best way to learn Linux is to use it. Get a book and sit down with it and a computer already running your Linux distribution of choice and start playing with Linux. You'll find that learning Linux really isn't that tough after all. Have fun!
P/S Here you can find number of free Linux Books:
http://www.techbooksforfree.com/linux.shtml[
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