Quick Start Guide to Penetration Testing
Sagar Rahalkar
Bash Idioms: Write Powerful, Flexible, Readable Shell Scripts
Carl Albing & J P Vossen
Mastering Linux Administration
Alexandru Calcatinge & Julian Balog
Practical Linux Forensics
Bruce Nikkel
SSH Mastery: OpenSSH, PuTTY, Tunnels and Keys
Michael W Lucas