title: How to get the passenger_app_env value from shell?
body: <p>I am currently working on a shell script to manage a service who is part of a <code>Rails</code> App (Nginx + Phusion Passenger) and needs to be launched with <code>systemd</code> after Rails has started.</p>
  
  <p>As a requirement the script needs the Rails environment value and I would like to get it from Passenger (<code>passenger_app_env</code> value).</p>
  
  <pre><code># /etc/nginx/sites-enabled/webapp.conf:
  server {
      ...
      # Ensures that RAILS_ENV, NODE_ENV, etc are set to "staging"
      # when your application is started.
      passenger_app_env staging;
  }
  </code></pre>
  
  <p>I was trying with <code>passenger-config about OPTION</code>, <code>env</code>, and <code>printenv</code> to get that value but without luck.</p>
  
  <p>Does anybody know a way to get the value of <code>passenger_app_env</code> from the OS shell?</p>