Best book/source to learn the unix commands

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http://askubuntu.com – So I was intern at this company wherein they'd use just putty. Now I've never worked with unix commands, apart from the basic , compile code , run C code. But now I would love to know all the things about the unix. Starting off with the commands, from the most basic of all to the decent level. Also, moving forward, how the different folders/files are arranged in a unix (ubuntu is installed on my system) system. I have picked up a couple of books, but they dont seem to help. Can someone suggest a comprehensive book that'll fulfill my needs. Because, working with a GUI on ubuntu does not re (HowTos)