Unix: Penetration Testing: A Hands-On Introduction to Hacking by Georgia Weidman, no starch press, 2014
Most everything you need to know to get started as a penetration tester in less than 500 pages? This book provides a very practical hands-on introduction to the art of hacking. But you will need to sit yourself down and let your fingers get a lot of exercise before you put yourself on the market as a pro.
Story added 22. June 2014, content source with full text you can find at link above.