Although the main purpose of AppleScript is to manipulate GUI-based applications, it can also interact with other types of applications. Beneath Mac OS X's graphical desktop lies a very different user interface—the Unix command line—and AppleScript can work with this too.
The world of Unix offers scripters an endless source of free scriptable applications. Many free Unix applications are available, each performing little commands and actions. You can utilize these applications by running Unix command-line scripts, or shell scripts. In turn, you can run shell scripts from your AppleScripts by means of the Standard Additions
do shell script command.
Not only can you use the Unix command line from ...