gistfile1.rb

#!/usr/bin/ruby

require 'win32/registry'
Win32::Registry::HKEY_CURRENT_USER.open('Software\SimonTatham\PuTTY\Sessions') do |reg|
  reg.each_key do |skname, wt|
    reg.open(skname, Win32::Registry::KEY_READ|Win32::Registry::KEY_WRITE) do |sk|
      puts "#{sk.keyname} BCE #{sk.read_i('BCE')}"
      sk.write_i('BCE',1)
    end
  end
end