title: Which version of R is running in my computer?
body: <p>There are two R directories on my computer:<br>
  one is <code>/home/R-2.15.2</code>,the other is <code>/home/R-2.15.1</code>,<br>
  when I input <code>R</code> , I can start R, now I want to know which R is running: 2.15.1 or 2.15.2?  </p>