This tutorial assumes that you already know how to log in to your UNIX machine, bring up the bash shell, and run basic commands such as ls and cat. Getting to this point is fairly easy, but unfortunately this is the level that most users stay at indefinitely. This tutorial is intended to help you start to learn the more advanced features of using a shell, and specifically bash, one of the most powerful shells available.
Please note that most of the command themselves are not explained; you can examine their functionality yourself by either reading their man page, or just experimenting with them to see what they do.
Normally programs take input from our keyboard, and display the output to our screens. However, these are just the defaults – UNIX has the ability to redirect the input (commonly referred to as stdin, short for standard input) and output (commonly referred to as stdout, short for standard output).