In fact, my goal is to install Capistrano. Currently it requires Ruby version 2.x and higher. But Ruby is available max 1.9.3 in Debian 7. So I was faced with dilemma, which is written in the title of my question: What is the best way to update Ruby 2.x on Debian 7?
My experience does not allow me to choose one of those options that are available on the Internet, and some of it simply do not work.