To refer the script itself, we have 4 optional variables:

• $_SERVER[’PHP_SELF’]
• $_SERVER[’SCRIPT_NAME’]
• $_SERVER[‘REQUEST_URI’]
• $_SERVER[HTTP_REFERER]

The first three are exactly the same, they are all relative to URL, represent the current running script file. The last one, $_SERVER[HTTP_REFERER], normally used in a parent-child/context env (frameset, <form…>) to refer to parent’s script name.

When I run phpinfo.php in my pc’s xampp env, they look like the following:

• $_SERVER[“REQUEST_URI”]: /xampp/phpinfo.php
• $_SERVER[“SCRIPT_NAME”]: /xampp/phpinfo.php
• $_SERVER[“PHP_SELF”]: /xampp/phpinfo.php
• $_SERVER[“HTTP_REFERER”]: http://localhost/xampp/navi.php

$_SERVER[’PHP_SELF’] and $_SERVER[’SCRIPT_NAME’] reprent script name, without passed parameters; On the other side, $_SERVER[‘REQUEST_URI’] will be with the parameters, e.g: /example/index.php?a=test.

Normally I use largely $_SERVER[‘PHP_SELF’] in my codes to call the default php script; and $_SERVER[“HTTP_REFERER”] to refer to parent’s script.

A good reference is at: http://php.about.com/od/learnphp/qt/\_SERVER\_PHP.htm