Mod Rewrite and Using PHP's GET for URL's When not Following the Rules

I couldn't think of a good title for this, it's hard to explain. Basically, I have mod_rewrite setup on my server. It turns each ?a=1&b=2&c=3 etc into /1/2/3/

I want to implement a feature where I can do something like this: /login/?return_url=/home/ The return_url would change depending on where the user was last. I know there are other methods of finding out the return url, but I would like to keep it in the URL.

My issue is that the following does not work: /login/?return_url=/home/

However, /login.php?return_url=/home/ does work.

Why can't PHP see the return_url varia开发者_如何转开发ble in the first (preferred) situation?

Here's my current code:

RewriteRule ^(.*)/(.*)/(.*)/([A-Za-z0-9_-]+)/$ /?a=$1&b=$2&c=$3&d=$4 [L]
RewriteRule ^(.*)/(.*)/([A-Za-z0-9_-]+)/$ /?a=$1&b=$2&c=$3 [L]
RewriteRule ^(.*)/([A-Za-z0-9_-]+)/$ /?a=$1&b=$2 [L]
RewriteRule ^([A-Za-z0-9_-]+)/$ /?a=$1 [L]

The QSA directive is probably what you're looking for:

'qsappend|QSA' (query string append)
This flag forces the rewrite engine to append a query string part of the substitution string to the existing string, instead of replacing it. Use this when you want to add more data to the query string via a rewrite rule.

E.g.,

RewriteRule ^something/([0-9]+)$ something.php?id=$1 [QSA]

Will let something/9?key=val go to something.php?id=9&key=val