title: grep case sensitive [A-Z]?
body: <p>I cannot get <code>grep</code> to <strong>case sensitive</strong> search with this pattern</p>
  
  <pre class="lang-r prettyprint-override"><code>$ grep 'T[A-Z]' test.txt
  The Quick Brown Fox Jumps Over The Lazy Dog
  THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
  </code></pre>