pg_ctl - initialize, start, stop, or control a PostgreSQL server
pg_ctl {start|stop|restart|reload|status|promote} [-D DATADIR] [-m SHUTDOWN-MODE] [-w|-W]Options you will use
-D, --pgdata=DATADIR- location of the database storage area.
-m, --mode=MODE- smart, fast or immediate.
-w, --wait- wait until operation completes (default).
Try pg_ctl in a real terminal Free, in your browser - a real Ubuntu terminal to try it in, with missions that check your work.