CGI: Getting the Requested URL?

How do I get the URL that my script is being acessed from by the user?

Example: A script can be accessed by going to http://hosta.domain/script/, or http://hosta.domain/script/index.cgi, or http://hostb.domain/mirror/script/index.cgi. How can I tell which URL the user typed into their browser from within the script itself?

There should be a REQUEST_URI environment variable, or something very much like it. It contains the URI that the browser requested from the server.

Thank YOU captain obvious. Of course there should be one.

I'm asking what that variable is.

Truth be told, from your post I couldn't even deduce that you know what an environment variable is in the first place. So knowing that there IS an environment variable should help you with your search.

Now go ahead and try not to piss off those that might help you.