title: Grep not working with anchor tags
body: <p>I'm trying to find every word in <code>/usr/dict/words</code> whose characters match those of my name. I thought this would work:</p>
  
  <pre><code>cat /usr/dict/words | grep "^[mason]\+$"
  </code></pre>
  
  <p>but it doesn't print anything.</p>
  
  <p>That being said, when I run: </p>
  
  <pre><code>cat /usr/dict/words | grep -v [A-Zbcdefghijlkpqrtuvwxyz]
  </code></pre>
  
  <p>I get the right output. I'm really confused. What's going on?</p>