PHP script to scrape data from a gist page

gist_scrape.php

<?
function get_gist_url($id) {
  $data = file_get_contents("https://gist.github.com/$id");
  $pos1 = strpos($data, "/raw/$id");
  $pos2 = strpos($data, "\"", $pos1);
  $url = substr($data, $pos1, $pos2-$pos1); 
  return "https://gist.github.com$url";
}
$url = get_gist_url($_GET["id"]);
ob_start('ob_gzhandler');
echo file_get_contents($url);
echo "\n# $url\n"; 
?>