<?php   

$the_host = $_SERVER['HTTP_HOST'];//取得当前域名   

$request_uri = isset($_SERVER['REQUEST_URI']) ? $_SERVER['REQUEST_URI'] : '';//判断地址后面是否有参数   

if($the_host == 'baidu.com')//把这里的域名换上你想要的   

{   

    header('HTTP/1.1 301 Moved Permanently');//发出301头部   

    header('Location: http://www.baidu.com'.$request_uri);//跳转到你希望的地址格式   

}  

//实例应用

$the_host = $_SERVER['HTTP_HOST'];

$request_uri = isset($_SERVER['REQUEST_URI']) ? $_SERVER['REQUEST_URI'] : '';

if($the_host == 'baidu.com'||$the_host == 'www.baidu.com')

{

    header('HTTP/1.1 301 Moved Permanently');

    header('Location: http://www.romeozhou.com'.$request_uri);

}

?>