title: Copy files from one directory into an existing directory
body: <p>In bash I need to do this:</p>
  
  <ol>
  <li><p>take all files in a directory </p></li>
  <li><p>copy them into an existing directory</p></li>
  </ol>
  
  <p>How do I do this? I tried <code>cp -r t1 t2</code> (both t1 and t2 are existing directories, t1 has files in it) but it created a directory called t1 inside t2, I don't want that, I need the files in t1 to go directly inside t2. How do I do this?</p>