Show item as local task but hide if argument is not provided
I solve this by argument load function, but I don't think it is correct to do like this.

// Menu item change
//....
'system-log/%ebanq_custom_log_id/view' =&gt; array(
//....

/**
 * Implements hook_load().
 */
function ebanq_custom_log_id_load($arg) {
    if (!is_numeric($arg)) {
        return FALSE;
    }
    return $arg;
}