title: Shell can't find nginx
body: <p>try to prompt this command <code>nginx -V</code> but shell returns <code>fish: Unknown command “nginx”</code></p>
  
  <p>If I try <code>sudo service nginx status</code>
  I could see <code>Usage: /etc/init.d/nginx {start|stop|restart|reload|force-reload}</code></p>
  
  <p>Why <code>nginx -V</code> is not work?</p>