title: grep using output from another command
body: <p>Say I have <code>command1</code> which outputs this:</p>
  
  <pre><code>b05808aa-c6ad-4d30-a334-198ff5726f7c
  59996d37-9008-4b3b-ab22-340955cb6019
  2b41f358-ff6d-418c-a0d3-ac7151c03b78
  7ac4995c-ff2c-4717-a2ac-e6870a5670f0
  </code></pre>
  
  <p>I also have <code>command2</code> which outputs this:</p>
  
  <pre><code>b05808aa-c6ad-4d30-a334-198ff5726f7c
  59996d37-9008-4b3b-ab22-340955cb6019
  </code></pre>
  
  <p>Is there a way to grep the output from <code>command1</code> to not include any lines matched from <code>command2</code>, so that the final output would look like this?</p>
  
  <pre><code>2b41f358-ff6d-418c-a0d3-ac7151c03b78
  7ac4995c-ff2c-4717-a2ac-e6870a5670f0
  </code></pre>