sed & awk
Dale Dougherty & Arnold Robbins
Mastering OpenLDAP
Matt Butcher
The Wireshark Field Guide
Robert Shimonski
Mastering Linux Administration
Alexandru Calcatinge & Julian Balog
Linux Advanced Routing and Traffic Control HOWTO
Gregory Maxwell & Remco Mook & Martijn Oosterhout & Paul Schroeder & Jasper Spaans & Bert Hubert