Migrate rubygems to Ruby Enterprise Edition (REE) - Make REE install the gems used by your default ruby environment.

migrate_rubygems_to_ruby_enterprise_edition.rb

#!/usr/bin/ruby

# Migrate rubygems to Ruby Enterprise Edition (REE)
# Make REE install the gems used by your default ruby environment.

REE_PATH = ENV['REE_PATH'] || Dir.glob('/opt/ruby-enterprise-*').last

unless REE_PATH
  puts "Can't find path to ruby enterprise edition. Please use the following command:"
  puts "REE_PATH=/path/to/ruby-enterprise ruby migrate-rubygems-to-ree"
  exit 1
end

gem_cmd = REE_PATH + '/bin/gem'
options = 'install --no-rdoc --no-ri'

require 'rubygems'

# gem_list = ['activerecord-2.3.5', ...]
gem_list = Gem.source_index.map { |a| a.first }.sort

# gem_list_cmd = ['activerecord -v 2.3.5', ...]
gem_list_cmd = gem_list.map { |g| 
  a = g.split('-')
  a[0..-2].join('-') + ' -v ' + a[-1]
}

# install command
gem_list_cmd.each do |gem|
  puts cmd = [gem_cmd, options, gem].join(' ')
  system cmd
end