title: Bash regex: how to match n times using 'grep' or 'ls'
body: <p>I'd like to match n digits the following way with <code>grep</code> or <code>ls</code>:</p>
  
  <pre><code>echo "ABCD150915.7z" | grep "ABCD[[:digit:]]{6}.7z"
  </code></pre>
  
  <p>The above is not working and I've tried quite many ways now... How can this be done?</p>
  
  <p>I understand there are other ways, but please note that I want to know if this specifically is possible: <code>[[:digit:]]</code> and <code>{6}</code> using <code>grep</code> or <code>ls</code>.</p>