An alias simply substitutes a longer command when you type a shorter one. Functions let you use a series of commands to perform some action. The portion inside braces is known as the body of the function. You can also refer to the arguments by number. For more, see Introduction to shell scripting, section 18.1 .
Every process has at least three connections to the outside world.
The user can specify which locations to use. When you run a program from the shell, usually standard input comes from your keyboard and standard output and error both go to your screen. However, you can ask the shell to change these defaults. For example, the echo command sends it output to standard output, normally the screen. So you can simply say more myfile and the effect will be the same.