title: Determine if operating system is Mac
body: <p>I have been doing a lot of Googling recently to try and find a simple, easy php script that will identify if the user is on a Mac or not.</p>
  
  <p>I want to use this to tell users if the keyboard shortcut I am telling them is "control" or "command". I don't need to know the browser or anything, just if the computer is a Mac.</p>
  
  <p>Here is an outline of what I'm asking is possible:</p>
  
  <pre><code>if (operating_system == Mac)
  {
      echo "command";
  }
  else
  {
      echo "control";
  }
  </code></pre>