List of freely available system administrator books [closed]

Solution 1:

I use Python for system administration, this book is under GNU Free Documentation License: Dive into Python

This one is about the Linux Kernel: Linux Kernel in a Nutshell and published under Creative Commons Attribution-ShareAlike 2.5 license

O'Reilly has also published a number of Open Books. Learning Debian, Version Control with subversion, Using Samba are quite outdated but still interesting.

Solution 2:

• FreeBSD Handbook
• Mac OS X Server Reference Library
• Bind 9.6 Administrator's Reference Manual
• DNS for Rocket Scientists
• Reference documentation for all Juniper Networks products
• Cisco's reference guides
• Rosetta Stone for Unix (not a book, but a great reference for admins who operates on many kind of unix systems)