Installing a new ruby on MacOS with homebrew, chruby & ruby-install

ruby-upgrade.sh

#!/bin/bash -ex

# Assumes:
#   homebrew
#   chruby
#   ruby-install
#   postgres.app

# this bit might not be necessary, but can't hurt
brew upgrade ruby-install

# install the new ruby
ruby-install ruby 2.1.4

# make sure chruby can see the new ruby
source /usr/local/opt/chruby/share/chruby/chruby.sh

# make the new ruby active
chruby ruby-2.1.4

# update rubygems
gem update --system

# these gems are fequently used but often not defined in Gemfiles
gem install bundler pry omglog --no-ri --no-rdoc

# pg gem needs special flags, if we let bundler install it bad things will happen
PG_CONFIG_PATH=/Applications/Postgres.app/Contents/Versions/9.3/bin/pg_config
ARCHFLAGS="-arch x86_64" gem install pg --no-ri --no-rdoc -- --with-pg-config=$PG_CONFIG_PATH