How can I reboot my remote server ?

[eluser]RaiNnTeaRs[/eluser]
Hi all, I'm using linux ubuntu , and im trying to shutdown my server using php..
I've tried using bellow command, and it still doesnt work.

Code:

<?
exec('sh shutdown.sh');
?>

this is the cat result of shutdown.sh

Code:

echo mypassword | sudo -S bash
sudo reboot

Thx