Rbenv
Groom your app’s Ruby environment with rbenv.
How to use
apt-get update -qy
apt-get install -y git curl build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libssl-dev
cd
RBENV=~/.rbenv
RBENV_PLUGINS=$RBENV/plugins
git clone git://github.com/sstephenson/rbenv.git $RBENV
export PATH=$RBENV/bin:$PATH
eval "$(rbenv init -)"
git clone git://github.com/sstephenson/ruby-build.git $RBENV_PLUGINS/ruby-build
export PATH=$RBENV_PLUGINS/ruby-build/bin:$PATH
curl -fsSL https://github.com/rbenv/rbenv-installer/raw/master/bin/rbenv-doctor | bash
rbenv install 2.2.4
rbenv global 2.2.4