如何使用exec PHP关闭Ubuntu

<?php
exec('sudo shutdown -h now');
?>

<?php
$password = 'your_password_here';
$command = "sudo -S shutdown -h now";
$process = proc_open($command, array(0 => array('pipe', 'r'), 1 => array('pipe', 'w'), 2 => array('pipe', 'w')), $pipes);

if (is_resource($process)) {
    fwrite($pipes[0], $password . PHP_EOL);
    fclose($pipes[0]);
    $output = stream_get_contents($pipes[1]);
    fclose($pipes[1]);
    $error = stream_get_contents($pipes[2]);
    fclose($pipes[2]);
    $return = proc_close($process);

    if ($return === 0) {
        echo "Ubuntu系统已成功关闭。";
    } else {
        echo "关闭Ubuntu系统时出错。";
    }
} else {
    echo "无法执行命令。";
}
?>