This guide is simply a short summary of some of the available tools of a GNU/Linux based distribution. If you find a particular command interesting and useful, you can look up the on-line manual, or/and info page to learn more about how to use this command or check the HOWTO's online at Linux Documentation Project.
The manual/info pages will always be an up-to-date source of information on how to use the command. Also have a look at the documentation installed on your distribution, its normally located in /usr/share/doc.
Check the references section of this document, Bibliography, for some links to useful resources which were used in the creation of this document.
Of course if you are having trouble with a particular command try using a search engine such as Google or AllTheWeb, or search the usenet groups Google Groups. If you still can't find a solution, look for a mailing list which is related to the topic you are having trouble with, or try a forum which is related to the topic.
Commands from "Linux in a Nutshell 3rd Edition" as published by Orielly --- this document was not used in the creation of this guide, however it is a comprehensive guide to GNU/Linux Commands (it's an indexed listing). It lists and explains 379 commands taken from Linux in a Nutshell 3rd Edition.
The Linux Newbie Admin guide list of commands --- another list of commands from an excellent system administration guide for GNU/Linux.
Comptechdoc's Linux Command Quickreference Guide --- a good list of commands but only one line explanations of what they actually do...
SS64.com list of bash commands --- this page lists commands and links to their man pages online.
If you wish to learn more about GNU/Linux on a variety of subjects also see the various online (free) tutorials published by IBM Developerworks.
If you are looking for a general reference to everything GNU/Linux try the Rute User's Tutorial and Exposition. Or take a look at your distributions documentation, Debian maintains comprehensive documentation, debian documentation site.
The most obvious place to look for documentation is to find the homepage of the program. Although sometimes there are other sources of information such as the Linux Documentation Project or various online HOWTO's or similar guides. They are usually easily found using search engines. Try large sites such as (ibiblio) the publics library and digital archive or TuxFinder which can search for documentation.
Below is a very short list of some further reading for a few of the more complex tools:
OpenSSH OpenSSH manual page
vim The Vim HOWTO
emacs The Emacs HOWTO
RPM RPM HOWTO
Samba Samba documentation site
ImageMagick ImageMagick command-line tools
Bash scripting Advanced bash scripting guide
rsync rsync homepage
Then type / (slash; runs a search) then the string “toolbox” (toolbox is the string to be searched for) then hit enter (follow hyperlink) and then go down to the “Toolbox introduction” section and hit enter. This will give you access to the article.
Other articles online include an: Orielly article on the UNIX tools philosophy.
While manual pages and info pages are usually installed with the program itself they are also available online if you need them, the listed links are usually listed by category or by the man page sections.