如何在php中运行外部程序

I need regular reload named zones from external clients. But all "remote execution" functions are disabled (system, exec, shell_exec etc.)

I have script like this (with basic http auth):

$ip = $_SERVER['REMOTE_ADDR'];
$user = $_SERVER['REMOTE_USER'];

if (isset($ip) && isset($user)) {
  // .... zone managment - nsupdate
  // reload zone
  shell_exec("/usr/sbin/rndc reload");
}

Is it possible to run this rdns/nsupdate another way?