<?php
global $logfile;
if (isset($_SERVER['DOCUMENT_ROOT'])) {
  $logfile=$_SERVER['DOCUMENT_ROOT']."/debug/debug.log";
}
 else {
   $logfile="/tmp/php_debug.log";
 }

function dl($s) {
  global $logfile;
  file_put_contents($logfile,$s,FILE_APPEND);
}