title: Using docker/docker-machine in multiple Terminal tabs on OSX
body: <p>I had docker wokring in one tab but started using it for something else. I opened a new tab and tried to run <code>docker build</code> but got this error:</p>
  
  <pre><code>Cannot connect to the Docker daemon. Is the docker daemon running on this host?
  </code></pre>
  
  <p>Running <code>docker-machine env default</code> gave this error:</p>
  
  <pre><code>Error checking TLS connection: Host is not running
  </code></pre>
  
  <p>I then ran <code>docker-machine start default</code> got this (it hung forever):</p>
  
  <pre><code>Starting "default"...
  (default) Waiting for an IP...
  </code></pre>
  
  <p>When I closed the original tab I had used docker in, I then ran <code>docker-machine start default</code> again and got:</p>
  
  <pre><code>Starting "default"...
  Machine "default" is already running.
  </code></pre>
  
  <p>And everything works fine in that tab now.</p>
  
  <p>How do I get docker commands to work in more than one Terminal tab?</p>