How to get the real URL after file_get_contents if redirection happens?

You might make a request with cURL instead of file_get_contents().

Something like this should work...

$ch = curl_init();
curl_setopt($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);
if(preg_match('#Location: (.*)#', $a, $r))
 $l = trim($r[1]);

Source

It seems that your nginx configuration is causing the problems.

Its totally possible that nginx is modifying the response headers. This is not by default - you could have a configuration that is aimed for it to behave as a reverse proxy etc.

Have you tried testing the redirect on a nginx with its default configuration?

My Problem is now solved, thanks to google and Daniweb here is solution

Dim req As HttpWebRequest = DirectCast(HttpWebRequest.Create("Your short URL here"), HttpWebRequest)
        Dim response As HttpWebResponse
        Dim resUri As String
        response = req.GetResponse
        resUri = response.ResponseUri.AbsoluteUri
        MsgBox(resUri)

this will return URL_2.