I'm interested in hearing about good open-source training materials for GNU/Linux use and administration. I've recently gotten interested in the field of online training, which we do some of at O'Reilly and which is clearly a growing trend in every field. Specifically, I'd asking for pointers to information that:
- ranges from basic Bash shell commands to configuration and monitoring of major Internet services, with a focus on GNU/Linux;
- is specifically designed and formatting for self-paced training, such as modules with questions and exercises;
- is under a free license, such as Creative Commons Share-Alike;
- is accurate, well-paced, and otherwise of high quality; and
- is preferably in English, but otherwise in a popular European language such as Spanish, French, Portuguese, etc.