title: Docker unknown shorthand flag: 'a' in -aq)
body: <p>I have multiple docker (version 18.09.0, build 4d60db4) containers running and I wish to stop them all at once. <a href="http://blog.baudson.de/blog/stop-and-remove-all-docker-containers-and-images" rel="noreferrer">This blog post</a> shows concisely exactly how to achieve this, great! </p>
  
  <p>I can list all containers using <code>docker ps -aq</code> and have no issues. </p>
  
  <p>However, when trying to stop all containers using the output of <code>docker ps -aq</code>, i.e. <code>docker stop $(docker ps -aq)</code>, I receive the following error:</p>
  
  <blockquote>
    <p><code>unknown shorthand flag: 'a' in -aq)</code></p>
  </blockquote>
  
  <p><strong>EDIT:</strong> I'm running Windows 10 Version 10.0.17134.407 in a standard (elevated) command prompt.</p>
  
  <p>Can anyone shed any insight into this?</p>
  
  <p>Thanks.</p>