$ sudo apt-get update
$ sudo apt-get install ruby-dataobjects-postgres 

ruby-dataobjects-postgres is installed in your system.

Make ensure the ruby-dataobjects-postgres package were installed using the commands given below,

$ sudo dpkg-query -l | grep ruby-dataobjects-postgres *

You will get with ruby-dataobjects-postgres package name, version, architecture and description in a table

ruby-dataobjects-postgres package basic information: