title: Looping through a file and removing certain lines
body: <p>I want to loop through a file and remove certain lines. Example file: </p>
  
  <p><strong>test.txt</strong></p>
  
  <pre><code>a
  b
  c
  d
  </code></pre>
  
  <p>What I have:</p>
  
  <pre><code>FILE=/tmp/test.txt
  while read FILE
  do
    # if the line starts with b delete it otherwise leave it there
    ?
  done
  </code></pre>