// выводим в браузер
if (file_exists($fName)) {
  header('Content-Description: File Transfer');
  header('Content-Type: application/octet-stream');
  header('Content-Disposition: attachment; filename="'.basename($fName).'"');
  header('Content-Transfer-Encoding: binary');
  header('Expires: 0');
  header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
  header('Pragma: public');
  header('Content-Length: ' . filesize($fName));
  ob_clean();
  flush();
  readfile($fName);
  exit;
}