if (!-d $request_filename){
    set $rule_0 1$rule_0;
}
if (!-f $request_filename){
    set $rule_0 2$rule_0;
}
 rewrite ^/post_([0-9]+)\.html$ /?mod=post&id=$1;
 rewrite ^/([a-zA-Z0-9_-]+).html$ /index.php?mod=$1;