Unix in a Nutshell: A Desktop Quick Reference - Covers GNU/Linux, Mac OS X,and Solaris (In a Nutshell (O'Reilly))
Learning Unix for OS X: Going Deep With the Terminal and Shell
The Linux Command Line: A Complete Introduction
LINUX: The Ultimate Beginner's Guide!
Learning the vi and Vim Editors: Text Processing at Maximum Speed and Power
Learning the bash Shell: Unix Shell Programming (In a Nutshell (O'Reilly))
Classic Shell Scripting: Hidden Commands that Unlock the Power of Unix
Macintosh Terminal Pocket Guide: Take Command of Your Mac