title: Does Mac OS X use Linux?
body: <p>The title says it all. At my job I've been asked to install a Ubuntu Linux system on a Virtualbox among other things so I can ssh into a development environment. This got me wondering about Operating Systems. I understand that Apple's is Mac OS X, but I just want to know if Mac OS X uses Linux or not. In August, I'm thinking of signing up for a Linux class on Edx.org so I can get better with the command line. I want to know if it will be a waste of time or not.</p>
  
  <p>I've already looked up the history of Linux, Looked it up on Wikipedia, and googled it but surprisingly I didn't find an answer to this question. So once again, does Mac use Linux?</p>