How a script is interpreted, depends on the server. You cannot download a script that runs on the server, because it runs remotely and you only see the output of the script.

If someone puts the source online, it will often be as a text file or, more likely, in a .tar.gz or .zip file. These you can download and view.

The source code for the engine that powers PerlMonks is available here.

For other cgi scripts, why not try the monastry's very own Super Search to find sample scripts.

Good luck.

cLive ;-)