<?php

  if (isset($_POST['name'])) {
    $filePath = "pdfurl-guide.pdf";
    header("Content-Type: application/octet-stream");
    header("Content-Disposition: attachment; filename=" . basename(urlencode($filePath)));
    header("Content-Type: application/octet-stream");
    header("Content-Type: application/download");
    header("Content-Description: File Transfer");
    $fp = fopen($filePath, "r");
    while (!feof($fp)) {
      echo fread($fp, 65536);
      flush();
    }
    fclose($fp);
    die();
  }

?>

Please fill out the following form to download:
<form method="post" action="">
  Name: <input type="text" name="name" /><br />
  <input type="submit" />
</form>