title: npm command not available in Docker container
body: <p>I use this:</p>
  
  <pre><code>RUN sudo apt-get install -y nodejs
  </code></pre>
  
  <p>and then we link nodejs executable to node like so:</p>
  
  <pre><code>RUN sudo ln -s `which nodejs` /usr/bin/node
  </code></pre>
  
  <p>that's all well and good, but for some reason the "npm" command is not available after installing nodejs.</p>
  
  <p>Why would that be? I thought npm was always bundled with nodejs? What do I need to do to get npm installed too? I am certain that nodejs is installed, but npm does not appear to be present, <code>$(which npm)</code> yields nothing.</p>