Learning the bash Shell: Unix Shell Programming (In a Nutshell (O'Reilly))

sed & awk: UNIX Power Tools (Nutshell Handbooks)

Bash Pocket Reference: Help for Power Users and Sys Admins

Classic Shell Scripting: Hidden Commands that Unlock the Power of Unix

Learning the vi and Vim Editors: Text Processing at Maximum Speed and Power

bash Cookbook: Solutions and Examples for bash Users

grep Pocket Reference: A Quick Pocket Reference for a Utility Every Unix User Needs (Pocket Reference (O'Reilly))

Wicked Cool Shell Scripts, 2nd Edition: 101 Scripts for Linux, OS X, and UNIX Systems

Managing Projects with GNU Make: The Power of GNU Make for Building Anything (Nutshell Handbooks)

Learning the Unix Operating System: A Concise Guide for the New User (In a Nutshell)

Linux Command Line and Shell Scripting Bible