nginx: [Emerg] неизвестная переменная «script_filename»

Я получаю эту ошибку при попытке использовать script_filename

nginx: [emerg] unknown "script_filename" variable
nginx: configuration file /etc/nginx/nginx.conf test failed

тем не мение script_filename определяется в: fastcgi_params

fastcgi_param  QUERY_STRING       $query_string;
fastcgi_param  REQUEST_METHOD     $request_method;
fastcgi_param  CONTENT_TYPE       $content_type;
fastcgi_param  CONTENT_LENGTH     $content_length;
fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
fastcgi_param  SCRIPT_NAME        $fastcgi_script_name;
fastcgi_param  REQUEST_URI        $request_uri;
fastcgi_param  DOCUMENT_URI       $document_uri;
fastcgi_param  DOCUMENT_ROOT      $document_root;
fastcgi_param  SERVER_PROTOCOL    $server_protocol;

fastcgi_param  GATEWAY_INTERFACE  CGI/1.1;
fastcgi_param  SERVER_SOFTWARE    nginx/$nginx_version;

fastcgi_param  REMOTE_ADDR        $remote_addr;
fastcgi_param  REMOTE_PORT        $remote_port;
fastcgi_param  SERVER_ADDR        $server_addr;
fastcgi_param  SERVER_PORT        $server_port;
fastcgi_param  SERVER_NAME        $server_name;

Конфигурация nginx:

    server {

        listen 80;
        server_name domain.com;
        access_log  /var/log/nginx/access.log  main;
        error_log  /var/log/nginx/error.log debug;
        root /home/username/public_html;
fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
        include /etc/nginx/fastcgi_params;

    if ($script_filename !~ "sss.php"){
    set $cond "true";
    }
    if ($script_filename !~ "word-administrator"){
    set $cond "true";
    }

        location ~ \.php$ {
                    fastcgi_index  index.php;
                    fastcgi_pass 127.0.0.1:9000;
fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
                    include /etc/nginx/fastcgi_params;
         }

    }

Такая же ошибка появляется в любом месте, например:

location / {
if ($script_filename !~ "sss.php"){
set $cond "true";
}
if ($script_filename !~ "word-administrator"){
set $cond "true";
}
}

версия nginx: nginx / 1.2.3

Как я могу это исправить?