title: What does IFS= do in this bash loop: `cat file | while IFS= read -r line; do ... done`
body: <p>I'm learning bash and I saw this construction:</p>
  
  <pre><code>cat file | while IFS= read -r line;
  do
      ...
  done
  </code></pre>
  
  <p>Can anyone explain what <code>IFS=</code> does? I know it's input field separator, but why is it being set to nothing?</p>