PostgreSQL connect to database using psql
To connect to the PostgreSQL database server using psql command line, run
su - postgres
psql
If you have a PostgreSQL user and password, you can use
psql -h SERVER_IP_HERE -p 5432 -U USER_NAME_HERE -W
Example
psql -h students.arrhwfpckmeo.ap-southeast-2.rds.amazonaws.com -p 5432 -U aite_students -W
-W option is to force asking password.
See PostgreSQL