$ sudo apt-get update
$ sudo apt-get install crystalspace-glshader-cg 

crystalspace-glshader-cg is installed in your system.

Make ensure the crystalspace-glshader-cg package were installed using the commands given below,

$ sudo dpkg-query -l | grep crystalspace-glshader-cg *

You will get with crystalspace-glshader-cg package name, version, architecture and description in a table

crystalspace-glshader-cg package basic information: