title: How can I remove characters from filenames with awk or sed?
body: <p>I have more than 1000 files that look like this. </p>
  
  <pre><code>kkk1a2o_A.txt
  kkk1a73_A.txt
  kkk2chj_A.txt
  </code></pre>
  
  <p>I would like to change the name of each file as follows</p>
  
  <pre><code>1a2o.txt
  1a73.txt
  2chj.txt
  </code></pre>
  
  <p>How can I do this with awk or sed?</p>