title: Unix command to find string set intersections or outliers?
body: <p>Is there a UNIX command on par with </p>
  
  <pre><code>sort | uniq
  </code></pre>
  
  <p>to find string set intersections or "outliers".</p>
  
  <p>An example application: I have a list of html templates, some of them have {% load i18n %} string inside, others don't. I want to know which files don't.</p>
  
  <p><strong>edit:</strong> grep -L solves above problem. </p>
  
  <p>How about this:</p>
  
  <p>file1:</p>
  
  <pre><code>mom
  dad
  bob
  </code></pre>
  
  <p>file2:</p>
  
  <pre><code>dad
  </code></pre>
  
  <p>%intersect file1 file2</p>
  
  <pre><code>dad
  </code></pre>
  
  <p>%left-unique file1 file2</p>
  
  <pre><code>mom
  bob
  </code></pre>