Aliases are shortcuts, that is, command names that you can create to take the place of longer commands.
Functions are like aliases, except that they allow more complex expressions.
An alias command consists of the command alias , the name you want to give the alias, and a definition that contains the actual command for which you are creating an alias. Two sample alias commands appears below. The first example makes the rm command prompt you before it removes a file. To use the newly-created aliases and functions in your current session, you must enter the command . Otherwise, the new aliases and functions will not be available until the next time you log in.