postgres create a user with password 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: postgres create admin user with password
sudo -u postgres createuser -s -i -d -r -l -w <<username>>
sudo -u postgres psql -c "ALTER ROLE <<username>> WITH PASSWORD '<<password>>';"