title: Values for os.family in Maven profile activation condition
body: <p>Maven allows to activate certain build profiles based on the operating system family it runs on, for example:</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;profile&gt;
      &lt;activation&gt;
          &lt;os&gt;&lt;family&gt;Windows&lt;/family&gt;&lt;/os&gt;
      &lt;/activation&gt;
  &lt;/profile&gt;
  </code></pre>
  
  <p>There is a number of question around this: what are allowed values for <code>os.family</code> then? Are they case sensitive? Does Linux come across as <code>Unix</code>? Or <code>unix</code>? And so on.</p>
  
  <p>Where can I find information about allowed values &ndash; or, at least, where does Maven take these values from? Environment variables?</p>