php 从源 url 获取重定向的 url

Question

我有这个链接:

http://libero-news.it.feedsportal.com/c/34068/f/618095/s/2e34796f/l/0L0Sliberoquotidiano0Bit0Cnews0C12735670CI0Esaggi0Eper0Ele0Eriforme0Ecostituzionali0EChiaccherano0Ee0Eascoltano0Bhtml/story01.htm

如果你访问它，它会变成:

http://www.liberoquotidiano.it/news/1273567/I-saggi-per-le-riforme-costituzionali-Chiaccherano-e-ascoltano.html

如何从第一个链接获取第二个链接？

我已经试过了，但没有用，返回给我相同的第一个链接:

<?php
$url="http://libero-news.it.feedsportal.com/c/34068/f/618095/s/2e34796f/l/0L0Sliberoquotidiano0Bit0Cnews0C12735670CI0Esaggi0Eper0Ele0Eriforme0Ecostituzionali0EChiaccherano0Ee0Eascoltano0Bhtml/story01.htm";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
$a = curl_exec($ch);
print_r($a);echo"<br>";
if(preg_match('#Location: (.*)#', $a, $r)){
   $l = trim($r[1]);
   echo $l;
}else echo "not working";

非常感谢。

Answer 1

感谢@king-isaac以下代码已经过测试并且可以正常工作。

<?php 

$url="http://libero-news.it.feedsportal.com/c/34068/f/618095/s/2e34796f/l/0L0Sliberoquotidiano0Bit0Cnews0C12735670CI0Esaggi0Eper0Ele0Eriforme0Ecostituzionali0EChiaccherano0Ee0Eascoltano0Bhtml/story01.htm";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true); // Must be set to true so that PHP follows any "Location:" header
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$a = curl_exec($ch); // $a will contain all headers

$url = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL); // This is what you need, it will return you the last effective URL

// Uncomment to see all headers
/*
echo "<pre>";
print_r($a);echo"<br>";
echo "</pre>";
*/

echo $url; // Voila
?>