title: Using Windows/DOS shell/batch commands, how do I take a file and only keep unique lines?
body: <p>Say I have a file like:</p>
  
  <pre><code>apple
  pear
  lemon
  lemon
  pear
  orange
  lemon
  </code></pre>
  
  <p>How do I make it so that I only keep the unique lines, so I get:</p>
  
  <pre><code>apple
  pear
  lemon
  orange
  </code></pre>
  
  <p>I can either modify the original file or create a new one.</p>
  
  <p>I'm thinking there's a way to scan the original file a line at a time, check whether or not the line exists in the new file, and then append if it doesn't. I'm not dealing with really large files here.</p>