title: Docker - check within the container if a directory is mounted from the host or not
body: <p>I have a need to check if a directory <strong>in my running container</strong> is mounted from the host or not.<br>
  Example: using the <code>docker run .... -v /host-data:/data ....</code> command.  </p>
  
  <p>If not mounted, I want to warn the user that data on this directory will be lost when the container is terminated...</p>