I assume you're referring to these lines:
Finally, start up the server.
$ sudo -u postgres postgres -D /usr/local/pgsql/data
If so, that starts the PostgreSQL server in blocking mode. It is running. It won't exit until told to, and that terminal won't return. It sounds like you'd prefer it to exit and keep running in the background, in which case you should use pg_ctl
to start the server instead.
The bigger problem is that those instructions are pretty stupid. You shouldn't be initdb
'ing a new cluster and starting a new server; you almost certainly have one installed and running. It's hard to say, since you didn't say how you installed PostgreSQL, what OS you're on, what PostgreSQL version you have, etc.
In general, though, you should be connecting to your existing PostgreSQL install. Use that, don't initdb
a new one. That's why the guide you were reading says:
This section may be unnecessary on your system. Check if your installation of postgres created a default database and start scripts for you.
Since you're using a stock Ubuntu install, please start by reading the Ubuntu introduction to PostgreSQL.
Then follow the setup guide starting at "create the database".