gistfile1.rb

# this ruby script generates a shell script to reinstall/recompile your gems
puts '#!/bin/bash'
puts 'export ARCHFLAGS="-arch x86_64"'
`gem list`.each do |line|
  if line =~ /\s*(.+)\s+\((.+)\)/
    gem_name, versions = [$1, $2]
    versions.split(/, /).each do |version|
      puts "gem install #{gem_name} --version='#{version}'"
    end
  end
end