title: Docker image of 32 bit Ubuntu
body: <ol>
  <li><p>I am looking a lightweight docker image with Ubuntu 32 bit. Where can I find it? </p></li>
  <li><p>When I put a command <code>docker build .</code> in my directory with Dockerfile I get output like:</p></li>
  </ol>
  
  <blockquote>
  <pre><code>ending build context to Docker daemon 10.21 MB
   Step 1 : FROM ubuntu
    ---&gt; 104bec311bcd
   Step 2 : ENV x /home/
    ---&gt; Using cache
    ---&gt; e38b022c91f8
   Step 3 : COPY ./x /home
    ---&gt; Using cache
    ---&gt; c4558c94236f
  </code></pre>
  </blockquote>
  
  <p>What does those "hashes" means? I mean for example <code>c4558c94236f</code>. And what about when it comes to cache?</p>