As root
you need to edit /etc/apt/sources.lst
Then add contrib
and non-free
at the end of each line that begins with deb
and deb-src
just like the example:
deb http://http.us.debian.org/debian jessie main contrib non-free
deb http://security.debian.org jessie/updates main contrib non-free
Save the file, and run ‘apt-get update‘ and optionally ‘apt-get upgrade‘ to activate the changes.
Thank you a lot @tfoote, your solution is gust perfect.
I perform this task on all my machines now:
sudo apt-get install software-properties-common -y && sudo apt-add-repository contrib -y # https://dragonserw.ru/wiki:debian