Hi,

You can install Postgresql database on your Ubuntu 18.04 with following commands:

$ sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt/ $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'
$ sudo apt install wget ca-certificates
$ wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
$ sudo apt update
$ sudo apt install postgresql-10 pgadmin4

After completion of installation run postgresql service with following command:

sudo systemctl restart postgresql

You can check the status of service with following command:

sudo systemctl status postgresql.service

This will give following output:

root@deepak-VirtualBox:/home/deepak# sudo systemctl status postgresql.service
  postgresql.service - PostgreSQL RDBMS
   Loaded: loaded (/lib/systemd/system/postgresql.service; enabled; vendor preset: enabled)
   Active: active (exited) since Wed 2019-01-30 14:38:20 IST; 12min ago
 Main PID: 22168 (code=exited, status=0/SUCCESS)
    Tasks: 0 (limit: 2320)
   CGroup: /system.slice/postgresql.service

Jan 30 14:38:20 deepak-VirtualBox systemd[1]: Starting PostgreSQL RDBMS...
Jan 30 14:38:20 deepak-VirtualBox systemd[1]: Started PostgreSQL RDBMS.

Thanks