Show message if header location redirect fails [duplicate]

Question

I need to redirect to an unknown address. If the address is not available I would like to show a message to the user. How to do that?

<?php
header("Location: http://www.example.com/"); 
exit;
?>

Answer 1

The most direct method is to just retrieve the page:

if (file_get_contents('http://www.example.com/') !== false) {
  header("Location: http://www.example.com/"); 
  exit;
}

http://php.net/manual/en/function.file-get-contents.php

However, this only tells you if SOMETHING is available at that page. It won't tell you if, for instance, you got a 404 error page instead.

For that (and to save the memory cost of downloading the whole page), you can just get_headers() for the URL instead:

$url = "http://www.example.com/";
$headers = get_headers($url);
if (strpos($headers[0],'200 OK') !== false) { // or something like that
  header("Location: ".$url); 
  exit;
}

Answer 2

You can check if url exist then redirect:

$url = 'http://www.asdasdasdasd.cs';
//$url = 'http://www.google.com';

if(@file_get_contents($url))
{
    header("Location: $url"); 
}
else
{
    echo '404 - not found';
}

Answer 3

You can do it using curl

      $ch = curl_init(); 
      curl_setopt($ch, CURLOPT_URL, "http://www.example.com/"); 
      $output = curl_exec($ch); 
      if(curl_errno($ch)==6)
        echo "page not found";
     else
      header("Location: http://www.example.com/");      

       curl_close($ch);