> echo "CREATE DATABASE testdb;" | psql -h localhost -d postgres -U dbadmin -W
Password: 
CREATE DATABASE

> echo "GRANT CONNECT ON DATABASE testdb TO dbuser;" | psql -h localhost -d testdb -U dbadmin -W
> echo "GRANT USAGE, CREATE ON SCHEMA public TO dbuser;" | psql -h localhost -d testdb -U dbadmin -W
> echo "GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA public TO dbuser;" | psql -h localhost -d testdb -U dbadmin -W
> echo "ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT, INSERT, UPDATE, DELETE ON TABLES TO dbuser;" | psql -h localhost -d testdb -U dbadmin -W
> echo "GRANT USAGE, SELECT ON ALL SEQUENCES IN SCHEMA public TO dbuser;" | psql -h localhost -d testdb -U dbadmin -W
> echo "ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT USAGE, SELECT ON SEQUENCES TO dbuser;" | psql -h localhost -d testdb -U dbadmin -W

> echo -e '\du\n\l\n' | sudo -u postgres psql
                             List of roles
 Role name |                         Attributes                         
-----------+------------------------------------------------------------
 dbadmin   | Create DB
 dbuser    | 
 postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS

                                                   List of databases
   Name    |  Owner   | Encoding | Locale Provider | Collate |  Ctype  | ICU Locale | ICU Rules |   Access privileges   
-----------+----------+----------+-----------------+---------+---------+------------+-----------+-----------------------
 postgres  | postgres | UTF8     | libc            | C.UTF-8 | C.UTF-8 |            |           | 
 template0 | postgres | UTF8     | libc            | C.UTF-8 | C.UTF-8 |            |           | =c/postgres          +
           |          |          |                 |         |         |            |           | postgres=CTc/postgres
 template1 | postgres | UTF8     | libc            | C.UTF-8 | C.UTF-8 |            |           | =c/postgres          +
           |          |          |                 |         |         |            |           | postgres=CTc/postgres
 testdb    | dbadmin  | UTF8     | libc            | C.UTF-8 | C.UTF-8 |            |           | =Tc/dbadmin          +
           |          |          |                 |         |         |            |           | dbadmin=CTc/dbadmin  +
           |          |          |                 |         |         |            |           | dbuser=c/dbadmin
(4 rows)


> echo 'CREATE TABLE testtab (id INTEGER GENERATED ALWAYS AS IDENTITY PRIMARY KEY, code VARCHAR(10));' | psql -h localhost -d testdb -U dbuser -W
Password: 
CREATE TABLE

> echo '\dt' | psql -h localhost -d testdb -U dbuser -W
Password: 
         List of relations
 Schema |  Name   | Type  | Owner  
--------+---------+-------+--------
 public | testtab | table | dbuser
(1 row)

> echo "INSERT INTO testtab (code) VALUES ('ABC');" | psql -h localhost -d testdb -U dbuser -W
Password: 
INSERT 0 1

> echo "SELECT * FROM testtab;" | psql -h localhost -d testdb -U dbuser -W
Password: 
 id | code 
----+------
  1 | ABC
(1 row)