It doesn't matter what you call a file in Linux. It will be executed as long as it has execute permission. You don't need extensions, though a lot of people do use .sh. The most important thing to have in a script is the shell to run as the first line. This typically looks like: #!/bin/sh This tells the system that this script should be interpreted by /bin/sh. Normally, a number sign is a comment character, but when followed by the exclamation mark and on the first line of a script, it gets the special treatment. If you replaced that line with: #!/usr/bin/perl instead, the script would be processed by perl. It's generally a good idea to give the complete path. As to your second question, parameters are called $1, $2, and so forth in shell scripts. $0 is the command name, so you can tell what a command was called by the user. Hope this helps.
