重定向开始下载

I'm writing a php script. In download part I have to redirect an url to start download. However, when I click the button .jpg files are opened in the new tab. How can I convert it to download format.

<?php 

$url= @$_GET['url'];

function redirect($url){
    if (headers_sent()){
        die('<script type="text/javascript">window.location=\''.$url.'\';</script‌​>');
            }else{
                header('Location: ' . $url);
                die();
            }    
    }

redirect($url);

Multiple solutions to download...

Like a download button:

<a target="_blank" download="download" href="http://www.w3schools.com/css/trolltunga.jpg">Test</a>

You could also do a file_get_contents of the file in PHP and serve it with the appropriate headers like here:

how to download a file from file_get_contents?

But not quite via a redirect, unless the source contains the appropriate headers. There's always the button hack as shown here:

Download image with JavaScript

Any of these suit your needs?