$ sudo apt-get update
$ sudo apt-get install doublecmd-plugins 

doublecmd-plugins is installed in your system.

Make ensure the doublecmd-plugins package were installed using the commands given below,

$ sudo dpkg-query -l | grep doublecmd-plugins *

You will get with doublecmd-plugins package name, version, architecture and description in a table

doublecmd-plugins package basic information: