if (substr($_SERVER['HTTP_HOST'], 0, 4) == "www.") {
$adres= substr($_SERVER['HTTP_HOST'], 4);
} else {
$adres = $_SERVER['HTTP_HOST'];
}

if($adres == "birdomain.com/birsayfa.html")
{
Header('Location:budomainegit.com/baskasayfa.html');
}