install_rubby.md

First, you install ruby-build and chruby. ruby-build is a program that knows how to download and build different ruby versions. chruby manages $PATH to control which ruby gets invoked in your shell. They work completely independently.

sudo su
cd /usr/src

git clone https://github.com/sstephenson/ruby-build.git
cd ruby-build
./install.sh
cd -

wget -O chruby-0.3.8.tar.gz https://github.com/postmodern/chruby/archive/v0.3.8.tar.gz
tar -xzvf chruby-0.3.8.tar.gz
cd chruby-0.3.8
make install
cd -

Then you install a rubby (still as root). chruby expects rubbies to live in /opt/rubies. I install bundler globally and install each project's deps inside the project with bundle --path.

mkdir -p /opt/rubies
ruby-build 2.1.0 /opt/rubies/2.1.0
/opt/rubies/2.1.0/bin/gem install bundler

Then you put chruby 2.1.0 in your .bashrc and work on projects like this:

bundle --path .bundle
bundle exec rspec

If you're binstub inclined you can also do:

bundle install --binstubs .bundle/bin --path .bundle

then add ./.bundle/bin to your $PATH

That and I prefer https://github.com/postmodern/ruby-install/ to ruby-build mostly because it doesn't need to updated as often in my experience.

using binstubs is a security issue when used with shared projects http://niczsoft.com/2013/10/please-hack-my-rails/

@mpapis, thanks for that. I read the article when it came out and choose what projects get the binstub treatment in my environment. Great reminder.