title: regex for one character or another?
body: <p>I'm searching for a regex code which lists all the lines that contain an a OR an i.
  I tryed this:</p>
  
  <pre><code>grep -E '[(a|i)]{1}' testFile.txt
  </code></pre>
  
  <p>but this gives me the words containing a or i and words that contain a en i.
  What's wrong?</p>