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If you are a developer for the GNU/Linux system, this book will help you to: Develop GNU/Linux software that works the way users expect it to. Write more sophisticated programs with features such as multiprocessing, multi-threading, interprocess communication, and interaction with hardware devices. Improve your programs by making them run faster, more reliably, and more [...]

This is a beginner guide to using Linux Download Link http://www.tuxradar.com/linuxstarterpack

A good book for Unix programming http://catb.org/~esr/writings/taoup/html/