title: sed remove lines that starts with a specific pattern
body: <p>I'm trying to use sed command with a regex pattern that works fine with grep. But it's not matching nothing with sed command.</p>
  <p>I have a text file and want to delete each line that starts with (wow or waw).</p>
  <p>This is the command I'm using But it's not working.</p>
  <pre><code>sed -i '/^w\(o\|a\)w/d' text.txt
  </code></pre>
  <p>I tried using the same pattern with grep and it works fine:</p>
  <pre><code>grep '^w\(o\|a\)w' text.txt 
  </code></pre>
  <p>Anything wrong with the regex in the sed command ?</p>