title: Batch rename file extensions, including subdirectories
body: <p>I'm renaming empty file extensions with this command:</p>
  
  <pre><code>rename *. *.bla
  </code></pre>
  
  <p>However, I have a folder with hundreds of such subfolders, and this command requires me to manually navigate to each subfolder and run it.</p>
  
  <p>Is there a command that I can run from just one upper level folder that will include all the files in the subfolders?</p>