php查询字符串标题

Hello I have a problem with header('Location: http://www.example2.com/'); while there is a query string.

Ok I will make the question easy to understand:

now I have a domain name http://example1.com/?url=url I want when someone want to access example1.com it redirects him to example2.com but if he types example1.com/?url=url nothing will happen so how can I do that please and thanks in advance

I assume you have index.php in root directory of domain example1.com. And you can use this;

<?php

if (empty($_GET["url"])) {
    header("Location:  http://www.example2.com/");
}

What do you use for redirecting? From your post's first line I assume, that you're redirecting the user via the PHP header function. So, check in PHP whether there is a query string or not:

<?php
if (empty($_SERVER["QUERY_STRING"]))
{
    header("Location:  http://www.example2.com/");
}
?>