title: File is not creating on heroku using cakephp
body: <p>I tried to make a file on heroku using PHP code:</p>
  
  <pre><code> $fh = fopen("../DownloadFiles/".$filename,'a');
  fwrite($fh,$s);
  </code></pre>
  
  <p>but the file has not been created and it is not showing any error. Please help.</p>