title: Can't start postgresql on Ubuntu 17.10
body: <p>Abandoning linuxbrew, installed postgresql using apt instead. Now I get this error:</p>
  <pre><code>$ /usr/lib/postgresql/9.6/bin/pg_ctl -D /var/lib/postgresql/9.6/main -l logfile start
  pg_ctl: could not open PID file &quot;/var/lib/postgresql/9.6/main/postmaster.pid&quot;: Permission denied
  </code></pre>
  <p>I tried running as superuser:</p>
  <pre><code>$ sudo /usr/lib/postgresql/9.6/bin/pg_ctl -D /var/lib/postgresql/9.6/main -l logfile start
  pg_ctl: cannot be run as root
  Please log in (using, e.g., &quot;su&quot;) as the (unprivileged) user that will
  own the server process.
  </code></pre>
  <p>I don't understand what user I should be logged in as.</p>
  <br>
  <h2>Original post:</h2>
  <p>I've brew installed postgresql, but having trouble starting it:</p>
  <pre><code>$ brew services start postgresql
  sh: 1: list: not found
  Error: Failure while executing:  load -w /home/me/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
  </code></pre>
  <p>The .plist file exists. Not sure what this error means! Same thing happens when running the command as root.</p>