title: How to restrict a find and replace to only one column within a CSV?
body: <p>I have a 4-column CSV file, e.g.:</p>
  
  <pre><code>0001 @ fish @ animal @ eats worms
  </code></pre>
  
  <p>I use <code>sed</code> to do a find and replace on the file, but I need to limit this find and replace to only the text found inside column 3.</p>
  
  <p>How can I have a find and replace only occur on this one column?</p>