你大部分都是对的。然而，有一点需要注意：$url 在你的上下文中没有任何意义。通过使用这样的方法进行调试，可以很容易地证明这一点

add_action(\'template_redirect\', \'post_redirect_by_custom_filters\');
function post_redirect_by_custom_filters() {
    var_dump($url);
    wp_die();
}

add_action(\'template_redirect\', \'post_redirect_by_custom_filters\');
function post_redirect_by_custom_filters() {
    global $post;

    // this array can contain category names, slugs or even IDs.
    $catArray = [\'grill-rezepte\',\'Test2\'];

    // get current path
    $url = $_SERVER[\'REQUEST_URI\']; 

    // slug is already in URL, return early
    if (strpos($url,\'grill-rezept\') !== false) {
        return;
    }

    if (is_single($post->ID) && has_category($catArray, $post)) {
        $new_url = "https://bbqpit.de/grill-rezepte/{$post->post_name}/";  
        wp_redirect($new_url, 301);
        exit;
    }
}