$ sudo apt-get update
$ sudo apt-get install gsql-postgresql-engine 

gsql-postgresql-engine is installed in your system.

Make ensure the gsql-postgresql-engine package were installed using the commands given below,

$ sudo dpkg-query -l | grep gsql-postgresql-engine *

You will get with gsql-postgresql-engine package name, version, architecture and description in a table

gsql-postgresql-engine package basic information: