.htaccess question - query sting param redirect

[LaoTzu]

$10 epass and my eternal gratitude for a working solution:

I need to 301 redirect urls with a specific query string parameter (any value) to my main url. In other words:

http://www.domain.com/index.php?[B]cat[/B]=x
http://www.domain.com/index.php?[B]cat[/B]=whatever

redirects to:

http://www.domain.com

(no file name (index.php), just the main domain.)

but

http://www.domain.com/index.php?[B]dir[/B]=x

stays unchanged.

[nation-x]

why use htaccess to do that? why not just use php?

[nation-x]

put this at the top of your index.php

Certain values

if (isset($_GET['cat'])) {
    switch ($_GET['cat']) {
        case 'x':
            header("HTTP/1.1 301 Moved Permanently");
            header("location: http://www.domain.com");
            header("connection: close");
            break;
       case 'whatever':
            header("HTTP/1.1 301 Moved Permanently");
            header("location: http://www.domain.com");
            header("connection: close");
            break;
    }
} 

Any Value

if (isset($_GET['cat'])) {
    header("HTTP/1.1 301 Moved Permanently");
    header("location: http://www.domain.com");
    header("connection: close");
} 

[LaoTzu]

Yo, you're awesome for posting that, but no dice. I tried the code in index.php but it had no affect. This script has so many .php functions and external files - totally beyond my grasp. That's why I was hoping for a neat and tidy .htaccess fix.
Hit me up with your epass though! mcurtis313 at gmail dot com

[drocd]

RewriteEngine on
RewriteCond %{QUERY_STRING} ^cat=.*$
RewriteRule .* http://www.domain.com [R=301,L]

[LaoTzu]

RewriteEngine on
RewriteCond %{QUERY_STRING} ^cat=.*$
RewriteRule .* http://www.domain.com [R=301,L]

So close!! The redirected URL is appended with the query string.
http://www.domain.com/?cat=x

I want to kill the trailing slash and query string for the canonical URL.

[drocd]

Okay, then change it to this:

RewriteEngine on
RewriteCond %{QUERY_STRING} ^cat=.*$
RewriteRule .* http://www.domain.com? [R=301,L]

[LaoTzu]

WINNER!
I've still got the trailing slash (www.domain.com/) but that's damn close.
Hit me up with your epass mcurtic313 a t gmail d o t com

[drocd]

no epass needed. just hit me up if you need a programmer in the future.

note: even if you put the url in your browser without the trailing slash, you'll see it refresh WITH the slash.

[LaoTzu]

You, sir, are the man. I will.