update-alternative.rb

#coding:utf-8

# Thanks to http://d.hatena.ne.jp/cuzic/20100101
system191 = ["/usr/", "1.9.1", 100]

commands = %w(ruby irb gem rake rdoc testrb erb)

[system191].each do |dir, suffix, priority|
  args = commands.map do |command|
    link = "/usr/bin/#{command}"
    fullpathcmd = "#{File.join(dir, "bin", command)}#{suffix}"
    if command == "ruby" then
      "--install #{link} #{command} #{fullpathcmd} #{priority}"
    else
      "--slave #{link} ruby-#{command} #{fullpathcmd}"
    end
  end.join(" ")
  altcmd = "sudo update-alternatives #{args}"
  system altcmd
end