title: grep lines that contain 1 character followed by another character
body: <p>I'm working on my assignment and I've been stuck on this question, and I've tried looking for a solution online and my textbook.</p>
  
  <p>The question is:</p>
  
  <blockquote>
    <p>List all the lines in the <code>f3.txt</code> file that contain words with a character <code>b</code> not followed by a character <code>e</code>.</p>
  </blockquote>
  
  <p>I'm aware you can do <code>grep -i 'b'</code> to find the lines that contain the letter <code>b</code>, but how can I make it so that it only shows the lines that contain <code>b</code> but not followed by the character <code>e</code>?</p>