php from shell

I want to write a utility script that I can execute from my bash shell
presently I run the script by typing

php myscript.php

where myscript.php is in my working directory.

I would like the script to do different things depending on how I call it (like a switch with a shell script)

I would like something similar to this

php myscript.php -D

is anything like this possible? If not how do i pass a variable to a php shellscript from the command line?

Yes, the CLI supports arguments. I'm not sharp enough on it yet to explain, but here's the reference....

$argc and $argv are the count and values, respectively, of arguments.

and if you want, you can do stuff like

#!/usr/local/bin/php
<?php
//code
?>