Looking for complete entered URL

I've written a script that logs all visits to a web site, complete with referrer and IP address. It also logs all 4xx errors. What I'd like to add to this is, if someone adds extra code after the page_name.php, to be able to capture any extra code and log that. I've tried: $_SERVER['QUERY_STRING'] $_SERVER['REDIRECT_QUERY_STRING'] $_SERVER['REDIRECT_URL'] but nothing seems to get logged. Is there a way, when either a false url is entered and a 404 is generated, or just when someone tacks on extra code to the URL, that I can grab that extra info? I'm looking for the complete URL that was entered by the user, not anything returned by the server. I've created my own 4xx_error.php files which calls my tracking script, along with creating the proper ErrorDocument lines in the main ..htaccess file. There are a lot of pages that have come up in my search, but nothing seems to pertain to what I'm trying to do. Thank you, Angela BTW, I know about Piwik and I use that, as well. This is something I'm doing on my own.