如果流脱机，则重定向到另一个页面（PHP）

$fp = fsockopen("www.example.com", 8000, $errno, $errstr, 1); //last param is timeout in seconds
if (!$fp) {
    header('Location: http://www.anothersite.com/some_message');
} else {
    fclose($fp); // radio OK
}

The code is not working and do not redirect.

ob_start();
//something
ob_end_clean(); //erase output
header('Location: ');