nginx下面CodeIgniter rewrite规则

server{
        listen 80;
        server_name  dev.xxx.bigoedu.com;
        root         /mnt/share/xxx.com/mfxxapi;
        index index.php;
        location ~ .*.php?$ {
            fastcgi_pass  127.0.0.1:9000;
            fastcgi_index index.php;
            include fastcgi.conf;
            index index.php index.html;
          }
        if (!-e $request_filename) {
         rewrite ^/(.*)$ /index.php?s=$1 last;
        }
}