Johan Mares has a recent post about using PHP on the command line:

I already knew how to run PHP scripts from the command line (CLI), although I never really used it. What was new to me was that there are 2 ways of doing this. The first one is by using the php command and the second, and new for me, is by adding a shebang on the first line of your script.

His first way is to run the PHP file through the interpreter directly (via a command line call to something like "php myfile.php"). The second it to actually include the path to the interpreter inside the PHP file itself and use the shell to execute the contents based on that (adding something like "#!/path/to/php" at the top). Then you just make the file executable and you can run it like any other binary file.