title: psql - every command returns FATAL: role "username" does not exist
body: <p>I installed postgresql server on Linux Mint, however, all I get from it is </p>
  
  <blockquote>
    <p>"FATAL:  role "username" does not exist".</p>
  </blockquote>
  
  <p>I've tried the following commands (probably some more):</p>
  
  <pre><code>psql
  psql --list
  psql \du
  psql \l
  psql -d template1
  createuser -s -r postgres
  </code></pre>
  
  <p>Same thing happens if I switch the user to postgres:</p>
  
  <pre><code>su - postgres
  </code></pre>
  
  <p>The postgresql version is 9.3.</p>
  
  <p>What's the correct approach on solving this? Thanks.</p>