title: Regex - Extract date from file name in list of files
body: <p>I have multiple files on a local directory named like this:</p>
  
  <pre><code>asd-3A-yyyyMMdd
  </code></pre>
  
  <p>Where yyyyMMdd represents a date.
  There are also files named:</p>
  
  <pre><code>bcd-3A-yyyyMMdd
  </code></pre>
  
  <p>And a bunch of files with different names, unnecesary to me.
  How can I extract only the date from the files starting with <strong>asd</strong>?
  Nothing I tried seems to work.</p>