title: php filemtime returning false other then the php application's root directory
body: <p>I am developing a php application using Ubuntu 11.10 in development environment.
  I have a directory '/usr/src/app_name/' which contains some pdf files.
  I need to retrieve the file names along with their last modification time.</p>
  
  <p>The following is the code snippet:</p>
  
  <pre><code>foreach (new DirectoryIterator('/usr/src/app_name') as $file) {
      if($file-&gt;isDot()) continue;
        print $file-&gt;getFilename().' : '.date ("F d Y H:i:s.", filemtime($file)).'&lt;br&gt;';
  }
  </code></pre>
  
  <p>I get the file names correctly but gives me:  PHP Warning:  filemtime(): stat failed.... and I get the time as 1 January, 1970.</p>
  
  <p>But, if I change the directory to application root directory i.e.</p>
  
  <pre><code>foreach (new DirectoryIterator('/var/www/app_name') as $file) {
    if($file-&gt;isDot()) continue;
      print $file-&gt;getFilename().' : '.date ("F d Y H:i:s.", filemtime($file)).'&lt;br&gt;';
   }
  </code></pre>
  
  <p>I get all the names of the php files of the app along with their last modification time.</p>
  
  <p>Any help on this will much appreciated....Thanks in advance.</p>