title: How to check and change the Nodejs version on Ubuntu?
body: <p>I am using Ubuntu Linux.</p>
  
  <p>How can I check current <code>nodejs</code> version? I guess, I have 6 version, but I am not sure.</p>
  
  <p>And is there way to change it, because I need 4 version. Can some one give step by step commands?</p>