title: How to extract custom file name using awk?
body: <p>Is it possible to use FILENAME in awk so it doesn't write out the whole name of the file but just a part of it?</p>
  
  <p>I would like to use:
  <code>awk '{print FILENAME; nextfile}' filename_number_something.txt</code></p>
  
  <p>but in a way that it only returns the <code>number</code> part of the file name.</p>