psql_and_django.sh

#!/bin/bash

apt update

# install on Ubuntu
apt-get install postgresql postgresql-contrib -y

# there is now a postgres user in /etc/passwd
# easy way to start it
service postgresql start

# now everything should be done as 'postgres' userr
su - postgres -c "createdb django"

# list databases for instance
su - postgres -c "psql -c '\l'"

That should work on both Ubuntu and Debian.
Tested on Docker "ubuntu" and "python"

# ./psql_and_django.sh
.....
[ ok ] Starting PostgreSQL 11 database server: main.
                              List of databases
   Name    |  Owner   | Encoding | Collate |  Ctype  |   Access privileges   
-----------+----------+----------+---------+---------+-----------------------
 django    | postgres | UTF8     | C.UTF-8 | C.UTF-8 | 
 postgres  | postgres | UTF8     | C.UTF-8 | C.UTF-8 | 
 template0 | postgres | UTF8     | C.UTF-8 | C.UTF-8 | =c/postgres          +
           |          |          |         |         | postgres=CTc/postgres
 template1 | postgres | UTF8     | C.UTF-8 | C.UTF-8 | =c/postgres          +
           |          |          |         |         | postgres=CTc/postgres```