title: How to remove a line containing specific string from file with sed command
body: <p>I have the following file :</p>
  
  <pre><code>#!example
  #!toto
  example
  #example
  ;example
  toto
  example
  </code></pre>
  
  <p>I want to remove the lines containing the string <code>"example"</code> except the lines start with <code>"#!"</code>.</p>
  
  <p>So the result file should be:</p>
  
  <pre><code>#!example
  #!toto
  toto
  </code></pre>
  
  <p>How to do it with only <code>sed</code> command?</p>