$ sudo apt-get update
$ sudo apt-get install opennebula-context 

opennebula-context is installed in your system.

Make ensure the opennebula-context package were installed using the commands given below,

$ sudo dpkg-query -l | grep opennebula-context *

You will get with opennebula-context package name, version, architecture and description in a table

opennebula-context package basic information: