All the Free Linux Documentation Resources You'll Ever Need
One of the biggest complaints that many people--especially IT administrators--have about open source software is that there isn't adequate documentation. For significant open source projects, though, the communities surrounding them tend to accumulate very extensive free documentation resources online. Whether you're new to Linux, or a seasoned Linux administrator, you can find hugely helpful resources online, without paying a dime. Here are some of the top free resources for Linux that we know of at OStatic, and some identified by others.
Linuxaria has a really in-depth collection of resources collected for Linux administrators. It includes documentation resources, downloadable tools, online sites and advice on specific commands that administrators should know about.
We've covered Ubuntu Pocket Guide and Reference before here, and you can download it for free here. The online book is mostly identical to the fee-based print version, and the author, Keir Thomas, has written a number of books on Linux. There are seven chapters in the reference guide, with many screenshots, and information on how to move from installation to advanced steps such as securing your Ubuntu system. In the appendix, you'll find a lot of reference information and documentation.
Linuxtopia has a huge number of online manuals available for particular Linux distros, as we covered here. There are reference guides on OpenSuse, Fedora, and many more titles. There are also reference guides available for many non-Linux open source applications.
Test Driving Linux: From Windows to Linux in 60 Seconds is a free online book that can get you started with both Linux and several open source programs. Beginners will find it approachable, and it covers everything from basic Linux commands to user interface conventions that differ between Linux and Windows.
Among educational Linux sites, my favorite remains Unix-Tutorials.com. Check out the long list of Linux topics you can dig into down the left rail of the home page, with content aggregated from around the web. These include nearly every popular Linux distro, in addition to other Unix-based titles such as Solaris. The site also includes tutorials on advanced topics such as integrating KVM virtualization with Linux server deployments. A little time spent with this site can pay big dividends.