$cmd = "ping 127.0.0.1";

    $descriptorspec = array(
       0 => array("pipe", "r"),  // stdin is a pipe that the child will read from
       1 => array("pipe", "w"),  // stdout is a pipe that the child will write to
       2 => array("pipe", "w") // stderr is a pipe that the child will read from
    );
    flush();
    $process = proc_open($cmd, $descriptorspec, $pipes, './', array());
    if (is_resource($process)) {
        while ($s = fgets($pipes[1])) {
            //Do whatever
            flush();
        }
    }