change hostname arX box

<?php

require_once('auth.php');

$hostname = $_POST['HOSTNAME'];

echo $hostname;

$file = "#This file was created by arX box configuration script
127.0.0.1       localhost $hostname
::1             localhost ip6-localhost ip6-loopback
fe00::0         ip6-localnet
ff00::0         ip6-mcastprefix
ff02::1         ip6-allnodes
ff02::2         ip6-allrouters";

$file_hostname = "/tmp/hostname";
$filename = "/tmp/hosts";

echo exec('sudo cp /etc/hostname /etc/hostname.backup-`date +%m-%d-%Y_%T`');
echo exec('sudo cp /etc/hosts /etc/hosts.backup-`date +%m-%d-%Y_%T`');

$fp = fopen ($filename, "w");
if ($fp) {
fwrite ($fp, $file);
fclose ($fp);
echo ("New hosts file written");
}
else {
echo ("File was not written");
}

$fp = fopen ($file_hostname, "w");
if ($fp) {
fwrite ($fp, $hostname);
fclose ($fp);
echo ("New hosts file written");
}
else {
echo ("File was not written");
}

echo exec('sudo mv /tmp/hostname /etc/hostname');
echo exec('sudo mv /tmp/hosts /etc/hosts');

echo ("hostname has been updated<br />");

shell_exec("sleep 10");
echo $hostname;
echo exec('sudo /bin/hostname <?php echo $hostname; ?>');
print ("<script>window.opener.location.reload();
//self.close();</script>");


echo '<input type="submit" value="Close" onclick="window.close()" />';

?>