PostgreSQL - query dallo script bash come utente del database 'postgres'

Prova questo:

#!/bin/bash
psql -U postgres -d database_name -c "SELECT c_defaults  FROM user_info WHERE c_uid = 'testuser'"

Oppure usando su :

#!/bin/bash
su -c "psql -d database_name -c \"SELECT c_defaults  FROM user_info WHERE c_uid = 'testuser'\"" postgres

E anche sudo :

#!/bin/bash
sudo -u postgres -H -- psql -d database_name -c "SELECT c_defaults  FROM user_info WHERE c_uid = 'testuser'"