[ubuntu] postgres, ubuntu how to restart service on startup? get stuck on clustering after instance reboot

I have a Postgres db 9.1 running on AWS EC2, with ubuntu 12.04.

I messed a lot with the instance (i.e installed all kinds of postgres X.X before i settled on 9.1).

Now after a month working on that db, I discovered that if I restart my instance postgres doesn't load correctly, its status says "Running clusters". this will last forever until I

sudo service postgresql restart

from terminal, and then it works again.

How do I add this line, to ubuntu startup so that each time it loads, it will restart this service, and hopefully solve my problem?

Also any other solution which might solve this.

The below command worked for me

sudo service postgresql restart

On Ubuntu 18.04:

sudo systemctl restart postgresql.service

ENABLE is what you are looking for

USAGE: type this command once and then you are good to go. Your service will start automaticaly at boot up

 sudo systemctl enable postgresql

DISABLE exists as well ofc

Some DOC: freedesktop man systemctl