title: Kill a postgresql session/connection
body: <p>How can I kill all my postgresql connections?</p>
  
  <p>I'm trying a <code>rake db:drop</code> but I get:</p>
  
  <pre><code>ERROR:  database "database_name" is being accessed by other users
  DETAIL:  There are 1 other session(s) using the database.
  </code></pre>
  
  <p>I've tried shutting down the processes I see from a <code>ps -ef | grep postgres</code> but this doesn't work either:</p>
  
  <pre><code>kill: kill 2358 failed: operation not permitted
  </code></pre>