$ sudo apt-get update
$ sudo apt-get install root-plugin-montecarlo-pythia8

root-plugin-montecarlo-pythia8 is installed in your system.

Make ensure the root-plugin-montecarlo-pythia8 package were installed using the commands given below,

$ sudo dpkg-query -l | grep root-plugin-montecarlo-pythia8*

You will get with root-plugin-montecarlo-pythia8 package name, version, architecture and description in a table

root-plugin-montecarlo-pythia8 package basic information: