htaccess and php

i have this gallery which has links like this.

gallery.php?user=205
205 here is a userid.

i am using mod_rewrite to have another script decide the userid from this url.

mysite.com/gallery/someuser

here "someuser" is username. the script in mod_rewrite is deciding the userid from the username. it's in the database.

i am using the header() function in the script to get the the gallery.php?user=$id

now the URL on the browser changes to gallery.php?user=205

for an example username "someuser" has a userid of 205.
so when someone visits http://mysite.com/gallery/someuser, mod_rewrite sends it to redirect.php?username=someuser

then redirect.php finds out the userid from the database and redirects to gallery.php?user=205.

as the redirect.php is using the header() function to redirect, the browser url changes to gallery.php?user=205.

is there a way to get around this and the URL in the browser stays the same?

gallery.php isnt a script of my own and i don't feel like editing it.

If you send a redirect header then the URL in the address bar will change. There is nothing you can do about that. If you want to ensure that this doesn't happen, set the appropriate $_GET variable and then include the gallery.php script.

is there no way to send some variable to an htaccess file?

You can set an environment variable and provided the server config allows you to read an environment variable from the htaccess file and provided Apache is running as a module. Again however, you don't need to do this, it is counter productive and pointless.

In an htaccess file you can access an environment variable using the following syntax: %{ENV:VarName}