gistfile1.rb

require 'rubygems'
#require 'bundler/setup'

GEMSET = 'rails_backup_migrate'

def rvm_do(version, command)
  # using inspect to place command in quotes, and escape other quotes
  script = "rvm #{version}@#{GEMSET} do #{command.inspect}"
  puts "about to execute: #{script}"
  `#{script}`
end

puts rvm_do('1.8.7', 'gem list')