title: How can I match a pattern as long as it's not at the beginning with regex?
body: <p>Assume the following strings:</p>
  
  <pre><code>aaa bbb ccc
  bbb aaa ccc
  </code></pre>
  
  <p>I want to match <code>aaa</code> as long as it is not at the start of the string. I'm trying to negate it by doing something like this:</p>
  
  <pre><code>[^^]aaa
  </code></pre>
  
  <p>But I don't think this is right. Using <code>preg_replace</code>.</p>