title: Difference between two files containing file names
body: <p>I have two files, <code>audit.txt</code> and <code>server.txt</code>, both contain filenames. I want to get only filenames that are present in <code>audit.txt</code> but not in <code>server.txt</code></p>
  <pre><code>audit.txt looks like
  
  filename1
  filename3
  filename2
  
  server.txt looks like
  
  filename1
  filename2
  </code></pre>
  <p>ideally i would want the difference in a 3rd file <code>missing.txt</code> that will contain <code>filename3</code> as per the example above.</p>
  <p>I have tried following but the <code>missing.txt</code> does not contain correct difference,</p>
  <p><code>comm -13 audit.txt server.txt &gt; missing.txt</code></p>