connect to database as user postgres code example
Example 1: create db user postgres
sudo -u postgres psql
postgres=# create database mydb;
postgres=# create user myuser with encrypted password 'mypass';
postgres=# grant all privileges on database mydb to myuser;
Example 2: How do I add a user to a postgres database? cli
psql=# grant all privileges on database <dbname> to <username>