> For example :
> if( $host ~* "(.*)\.[a-zA-Z0-9_-]*\.[a-zA-Z]{2,4}" )
> {
> addGet sd $1;
> }
>
> This code add "?sd=$1" or "&sd=$1" (if there are already arguments GET before or not)
>
> If not exist how can I do for write this function (or code who make the same ?)
>
> Thank you and sorry for my english (I'm french :p)

Hello.

If I understand correctly, you need something like this:

[code]
server {
listen 80;
server_name ~(.*)\..*\..*;
rewrite ^ /$request_uri&$1;
}
[/code]