Cheat sheet act as a reference tool which provides cut and paste kind of commands to complete a specific task. I often recommend following set of best cheat sheets to students and IT professionals. It include Linux/UNIX command and shell scripting.
This document is a collection of Unix/Linux/BSD commands and tasks which are useful for IT work or for advanced users. This is a practical guide with concise explanations, however the reader is supposed to know what s/he is doing.
=> Visit UNIX Toolbox
UNIX Tutorial for Beginners
A beginners guide to the Unix and Linux operating system. Eight simple tutorials which cover the basics of UNIX / Linux commands.
=> Visit UNIX Tutorial for Beginners
Linux Command and Learning Shell Tutorials
You have Linux installed and running. The GUI is working fine, but you are getting tired of changing your desktop themes. You keep seeing this “terminal” thing. Don’t worry, this site will show you what to do.
=> Visit Learning the shell
Learn UNIX in 10 minutes
This is something that I had given out to students (CAD user training) in years past. The purpose was to have on one page the basics commands for getting started using the UNIX shell (so that they didn’t call me asking what to do the first time someone gave them a tape).
=> Visit Learning UNIX in 10 minutes
How To Look Like A UNIX Guru
This lecture takes you through the basic commands and then shows you how to combine them in simple patterns or idioms to provide sophisticated functionality like histogramming. This lecture assumes you know what a shell is and that you have some basic familiarity with UNIX.
=> Visit How To Look Like A UNIX Guru
Linux command line reference
Another very good Linux command line reference for common operations.
=> Visit Linux Command Line Reference
Linux-Unix cheat sheets – The ultimate collection
Links to good reference material on various topics.
=> Visit Linux-Unix cheat sheets – The ultimate collection (dead link removed)
Alphabetical Directory of Linux Commands
This directory of Linux commands is from Linux in a Nutshell, 5th Edition. You can view total 687 commands to get a description and list of available options.
=> Visit directory of Linux commands
A Sysadmin’s Unixersal Translator (ROSETTA STONE)
A simple and nice lookup table for Linux / UNIX / BSD commands.
BigAdmin – System Administrator Resources and Community
Sun has BigAdmin portal with tons of information regarding UNIX, shell scripting and much more.
=> Visit BigAdmin System Administration Portal- Shell Commands (dead link removed, added archive.org link)
Please feel free to suggest some of the UNIX cheat sheets / tutorials, I did not mentioned here in the comments.