Unix System Administration
- Description of Unix internals by Frank G. Fiamingo at Ohio State University.
- http://8help.osu.edu/wks/sysadm_course/

Unix and Linux Commands
- Basic as well as more obscure commands for Unix/Linux operating systems.
- http://www.laynetworks.com/linux.htm

Online Single Unix Specification
- Ordering page for the Open Group's Single Unix Specification.
- http://www.unix.org/online.html

Unix Signals and Process Groups
- Short survey of Unix signal handling and process groups, conceptually and with interface descriptions. Compares System V Release 3, System V Release 4, BSD, and POSIX variants.
- http://world.std.com/~jimf/papers/signals/signals.html

pyttymon
- A simple daemon that monitors and limits usage of ttys. It is implemented in Python. A simple config file can specify monthly, daily, session, and idle limits based on tty, user, group, and ttys in use.
- http://freshmeat.net/projects/pyttymon/

Unix for Advanced Users
- Description of startup/shutdown, process management and memory management.
- http://www.uwsg.iu.edu/UAU/uau.html

Understanding Unix Concepts
- Conceptual discussion of Unix and Unix-like operating systems.
- http://www.uwsg.iu.edu/usail/index/concepts.html

First Edition Unix Manual
- The original Unix users manual.
- http://cm.bell-labs.com/cm/cs/who/dmr/1stEdman.html

Unix Manuals
- Brief Unix tutorial, online man pages and reference materials for the Unix operating system and common Unix utilities.
- http://www.unix-manuals.com

Unix Seventh Edition Manual
- Source material from Bell Labs.
- http://www.cs.bell-labs.com/7thEdMan/

Examware
- Unix tutorials, exercises and resources. Features on-line tests and training materials.
- http://examware.com/tutor5.html