Real path through aliases

Hi, I'm running PHP 4.3 and Apache 2, trying to figure something out. Is there a way from PHP to determine the real (harddrive, not URL) path being accessed by a URL? For example, if I want to know where on my harddrive http://localhost/web/ is, it's going to be DOCUMENT_ROOT/web, and I can make that work using REQUEST_URI for anything under my document root However, some of my folders are apache folder aliased to other parts of my harddrive. Example, http://localhost/music is actually f:/my documents/music/ Is there any way to let PHP figure this out automatically, without having to hardcode my script to look there every time? I really appreciate any answers you might have Thanks, Liam