title: Log4j FileNamePattern in DailyRollingFileAppender
body: <p>Is there a way to specify a pattern for an original filename?</p>
  
  <p>I essentially want to do the following:</p>
  
  <pre><code>&lt;param name="file" value="%d{yyyy/MM/dd HH:mm:ss}: %m%n_testlog.log"/&gt;
  </code></pre>
  
  <p>How would I go about doing this?</p>