title: Cannot execute RUN mkdir in a Dockerfile
body: <p>This is an error message I get when building a Docker image:</p>
  <pre><code>Step 18 : RUN mkdir /var/www/app &amp;&amp; chown luqo33:www-data /var/www/app
  ---&gt; Running in 7b5854406120 mkdir: cannot create directory '/var/www/app': No such file or directory
  </code></pre>
  <p>This is a fragment of Dockerfile that causes the error:</p>
  <pre><code>FROM ubuntu:14.04
  RUN groupadd -r luqo33 &amp;&amp; useradd -r -g luqo33 luqo33
  
  &lt;installing nginx, fpm, php and a couple of other things&gt;
  
  RUN mkdir /var/www/app &amp;&amp; chown luqo33:www-data /var/www/app
  VOLUME /var/www/app
  WORKDIR /var/www/app
  </code></pre>
  <p><code>mkdir: cannot create directory '/var/www/app': No such file or directory</code> sound so nonsensical - of course there is no such directory. I want to create it. What is wrong here?</p>