A script is simply a list of instructions that you may type at the keyboard, but put in a file with a very simple header ( "#!/bin/sh" ). They are then made executable using "chmod +x script-name".

These are normally stored in a well choosen directory and are run by type their pathname at the shell prompt. They can also be executed by other agents such as cron, or at startup/shutdown.

A commonly used naming convention is they have the shell type as an extension, eg *.sh, *.ksh, *.csh etc.