PHP redirect after checking website is up

I want to do 300 redirect by php but firs开发者_开发技巧t I want script will check whether the site is online or not if online then it will redirect else it will show unable to redirect. Can any one tell me how is possible? thanks

This should do it (edited for betterness)

$destination = 'http://www.google.com';
$ch = curl_init($destination);
// use request type HEAD because it's faster and lighter
curl_setopt($ch, CURLOPT_NOBODY, true);
// prevent curl from dumping any output
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
// prevent curl from producing any output
curl_setopt($ch, CURLOPT_HEADER, false);
// run request
curl_exec($ch);
// consider request a success if the HTTP Code is less than 400 (start of errors)
// change this to whatever you expect to get, e.g. "equal to 200 (OK)"
$success = (bool) ((int)curl_getinfo($ch, CURLINFO_HTTP_CODE) < 400);
curl_close($ch);
// redirect or die
if ($success) {
    header('Location: ' . $destination, true, 301);
} else {
    die('Unable to redirect to <a href="'.$destination.'">'.$destination.'</a>');
}