SLIM Framework PHP

$app->map('/users/posts/:id', function($id) use ($app) {

    if (!isset($_SESSION['user'])) {

        $app->redirect('/action/users/login/');
    }
    else{

        $app->render('something.php');
    }
})->via('GET', 'POST');

Hi All, im new with slim php framework. The problem i face now is when i pass parameter id at this url /users/posts/:id, i want to get the id value when im at something.php page. How can i do that ?

Thank you very much