title: How is a Docker Machine marked as active?
body: <p>I am working through the Docker Machine User Guide over at <a href="https://docs.docker.com/v1.5/machine/">https://docs.docker.com/v1.5/machine/</a>.</p>
  
  <p>It says: </p>
  
  <pre><code>You can see the machine you have created by running the docker-machine ls command again:
  
    $ docker-machine ls
    NAME      ACTIVE   DRIVER       STATE     URL
    dev       *        virtualbox   Running   tcp://192.168.99.100:2376
  
  The * next to dev indicates that it is the active host.
  </code></pre>
  
  <p>When I run this I don't see the * next to any machines. What do I need to do to make the machine be marked as active? Are there any benefits to this?</p>
  
  <p>For example, I am running the Docker Machine on Windows 10, by making it active does it mean I don't have to keep specifying the machine name in my commands such as <code>docker-machine env dev</code></p>