title: File upload temp dir empty
body: <p>I am looking at how file uploads work in PHP.</p>
  
  <p>When i upload a file, the <code>$_FILES</code> global says that the temp file name is <code>/tmp/phpDFUMAz</code> but this doesn't exist.</p>
  
  <p>If i check ini settings for <code>upload_tmp_dir</code> I can see the following:</p>
  
  <pre><code>upload_tmp_dir  no value
  </code></pre>
  
  <p>What exactly is PHP doing here? It has given a temp file name to the uploaded file but that doesn't exist on the server.</p>