title: No passwd entry for user 'postgres' error
body: <p>I'm trying to setup Postgres on Ubuntu 14.04 without success. After running </p>
  
  <blockquote>
    <p>sudo apt-get install libpq-dev python-dev</p>
  </blockquote>
  
  <p>and </p>
  
  <blockquote>
    <p>sudo apt-get install postgresql postgresql-contrib</p>
  </blockquote>
  
  <p>I've managed to install the packages successfully. However upon executing <strong>sudo su - postgres</strong>,  I'm receiving the following error:</p>
  
  <blockquote>
    <p>No passwd entry for user 'postgres'</p>
  </blockquote>
  
  <p>It seems like the installation did not create the user postgres as it is not in the /etc/passwd file. Reinstalling the package does not resolve the issue. How can I add the required postgres user?</p>