title: Copy files while skipping over files that exist - Unix
body: <p>I'd like to take a large folder (~100GB) and copy it over to another folder. I'd like it to skip any files that exist (not folders) so if <code>/music/index.html</code> does not exist it would still copy even though the <code>/music</code> directory already exists.</p>
  
  <p>I found <a href="https://superuser.com/questions/118781/copy-files-in-linux-avoid-the-copy-if-files-do-exist-in-destination">this</a>, but my shell is saying <code>-u</code> is not a valid argument.</p>
  
  <p>I don't know how <code>rsync</code> works, so please let me know if that's a better solution.</p>
  
  <p>Thanks.</p>