I know you can use shell_exec to execute a shell command and return the results via a string, like:
$result = shell_exec("cd /root");
echo $result; // "Directory Change Successful"
However, I'm not sure if you have login via root or anything like that, you can give it a try though. Most likely if you're on a *nix background it will give you the rights of Apache (Default nix setting for anything executed locally via Apache) or of PHP (some systems have alternate configurations). I have a feeling you're going to have trouble with this being that logging in as root is extremely insecure on a webserver. Let me know if you have any luck on this.
Cheers.