Practical Vim: Edit Text at the Speed of Thought
Learning the bash Shell: Unix Shell Programming (In a Nutshell (O'Reilly))
Linux Command Line and Shell Scripting Bible
sed & awk: UNIX Power Tools (Nutshell Handbooks)
Bash Pocket Reference: Help for Power Users and Sys Admins
Mastering Regular Expressions: Understand Your Data and Be More Productive
Linux Pocket Guide: Essential Commands
Linux Bible
grep Pocket Reference: A Quick Pocket Reference for a Utility Every Unix User Needs (Pocket Reference (O'Reilly))