title: How to match files *.R and *Rd with find utility?
body: <p>I would like to find all files that end with <code>.c</code>, <code>.R</code>, or <code>.Rd</code>. I tried </p>
  
  <pre><code>find . -iname "*.[cR]" -print
  </code></pre>
  
  <p>which gives all files that end with <code>.c</code> or <code>.R</code>. How can I additionally get <code>.Rd</code> files as well? I know that <code>[]</code> only matches one character, but I couldn't adjust it to provide <code>.Rd</code> files as well (tried to work with <code>|</code> or option <code>-regex</code> etc.)</p>