title: Copy all files with certain extension to another directory, while changing the extension
body: <p>I want to copy all the files with extension <code>aaa</code> from directory <code>a</code> to directory <code>b</code>, replacing the extension to <code>bbb</code>. I tried to do something like this:</p>
  
  <pre><code>ls a | grep \.bla$ | cut --delimiter=. -f 1 | xargs cp a/{}.aaa b/{}.bbb
  </code></pre>
  
  <p>But it's really off. I want a oneliner, and not a bash script.</p>