The Linux Command Line, 3rd Edition: A Complete Introduction
Learning the Korn Shell (Nutshell Handbooks)
The Linux Command Line, 2nd Edition: A Complete Introduction
bash Cookbook: Solutions and Examples for bash Users
Wicked Cool Shell Scripts, 2nd Edition: 101 Scripts for Linux, OS X, and UNIX Systems
Bash Pocket Reference: Help for Power Users and Sys Admins
Linux Phrasebook (Developer's Library)
SSH, The Secure Shell: The Definitive Guide