How to install PostgresSQL in Ubuntu?

$sudo apt-get update
$sudo apt-get install postgresql-9.3

$sudo -i -u postgres
$psql
$\q




https://www.digitalocean.com/community/tutorials/how-to-install-and-use-postgresql-on-ubuntu-14-04
http://askubuntu.com/questions/50621/cannot-connect-to-postgresql-on-port-5432