PHP $_SERVER help

[bwcc]

Im having a lapse in my recollection in using the $_SERVER predefined variables.

I have a reference to http://host/folder1/folder2/folder3/file1 in html.
The file that contains this reference may move from server to server. Instead of having to change that reference when I move the file, I would use:

PHP Code:

'http://'.$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF']; 


However, I want to drop the filename given in PHP_SELF, but keep the rest of the path.

Ideas?