Install gems from a gem list dump

gems_install.rb

#!/usr/bin/env ruby
#gem_cmd = ENV["GEM_CMD"] || 'sudo gem'
gem_cmd = 'gem'

STDIN.map { |l| l.strip }.each { |l| 
  gem, versions = l.split(' ', 2)
  versions = versions.gsub(/[\(\)]/, '').split(', ')
  
  versions.each { |version|
    cmd = "#{gem_cmd} install #{gem} -v #{version} --no-ri --no-rdoc"
    puts cmd if ENV["PRETEND"] or ENV["ECHO"]
    system cmd unless ENV["PRETEND"]
  }
}