Install ruby using rbenv, ruby-build, homebrew on Mac, with support for brew readline (history and unicode support on irb) and brew openssl.

install-ruby-via-homebrew.sh

brew update
brew install readline openssl rbenv ruby-build

# follow the instructions in `brew info rbenv` to set up rbenv

# or, if you already have those installed, just upgrade ruby-build to get the latest list of rubies

brew update
brew upgrade ruby-build

CONFIGURE_OPTS="--disable-install-doc --with-readline-dir=$(brew --prefix readline) --with-openssl-dir=$(brew --prefix openssl)" \
  rbenv install 2.2.3
  
rbenv global 2.2.3
gem update --system
gem install bundler


# on the project, when appropriate
rbenv local 2.2.3