title: replace spaces only in between quotation marks
body: <p>I have line from log file:</p>
  
  <pre><code>field 1234 "text in quotes" 1234 "other text in quotes"
  </code></pre>
  
  <p>I would like to replace spaces in between quotes, so I could than extract columns using space as delimiter. So the result could be something like</p>
  
  <pre><code>field 1234 "text@in@quotes" 1234 "other@text@in@quotes"
  </code></pre>
  
  <p>I was not able to find out working regex for sed myself.
  Thanks a lot for help.
  Martin</p>