The Restaurant at the End of the Universe
Douglas Adams
Modern Operating Systems
Andrew S. Tanenbaum & Herbert Bos
Learning the Bash Shell: Unix Shell Programming
Cameron Newham & Bill Rosenblatt
Unix and Linux System Administration Handbook 5th Edition
Evi Nemeth & Garth Snyder & Ben Whaley & Trent Hein
The Book of PF: A No-Nonsense Guide to the OpenBSD Firewall
Peter N. M. Hansteen