Shell Script to globally install gems for all Rubies in a RVM installation

example.sh

GEM_NAME=nokogiri GEM_VERSION=1.6.6.2 ./globally_install_gems.sh & GEM_NAME=nokogiri GEM_VERSION=1.6.6.1 ./globally_install_gems.sh & GEM_NAME=nokogiri GEM_VERSION=1.6.5 ./globally_install_gems.sh & GEM_NAME=nokogiri GEM_VERSION=1.6.4.1 ./globally_install_gems.sh & GEM_NAME=nokogiri GEM_VERSION=1.6.4 ./globally_install_gems.sh &

globally_install_gems.sh

#!/bin/bash

# Created by Tiago Amaro, 2015
# MIT License http://opensource.org/licenses/MIT

# Usage:
# GEM_NAME=json GEM_VERSION=1.8.2 ./globally_install_gems.sh

GEM_VERSION=${GEM_VERSION:="1.6.6.2"}
GEM_NAME=${GEM_NAME:="nokogiri"}
RUBY_VERSIONS=`rvm list strings`

for RUBY_VERSION in $RUBY_VERSIONS; do
  IS_GEM_INSTALLED=`rvm $RUBY_VERSION@global do gem list $GEM_NAME -i --version=$GEM_VERSION`
  if ! $IS_GEM_INSTALLED
  then
    echo "Installing $GEM_NAME $GEM_VERSION in Ruby $RUBY_VERSION global gemset"
    rvm $RUBY_VERSION@global do gem install $GEM_NAME --version=$GEM_VERSION --no-ri --no-rdoc &
  else
    echo "GEM $GEM_VERSION is already globally installed for $RUBY_VERSION"
  fi
done