title: Emacs Dired rename many files
body: <p>How to rename from:</p>
  
  <pre><code>VAR1_1F_text.txt
  VAR2_1F_text.txt
  VAR3_2F_text.txt
  </code></pre>
  
  <p>to</p>
  
  <pre><code>1F_VAR1_text.txt
  1F_VAR2_text.txt
  2F_VAR3_text.txt
  </code></pre>
  
  <p>How to switch parts of filenames?</p>