bash

Bash guide for beginners

“This is a practical guide which tries to give real-life instead of theoretical examples.” By making her book available for online reading, Machtelt Garrels introduces you to the wonders of task automation under Linux.
www.tldp.org

GNU Bash reference manual

“This manual is the definitive reference for GNU Bash, the standard GNU command-line interpreter. It covers the current major release of Bash (2.x).” Written by Chet Ramey and Brian Fox, the original developers of GNU Bash, the book is also available for online reading.
www.network-theory.co.uk

CLI magic: daily aliases

“GNU programs are rife with additional options. Some of these options are so useful you may want to create an alias.” Keith Winston manages to save a lot of time working at the shell.
www.linux.com