class Gem::Commands::UpdateCommand

def execute
  hig = {}
  if options[:system] then
    update_rubygems
    return
  else
    say "Updating installed gems"
    hig = {} # highest installed gems
    Gem::Specification.each do |spec|
      if hig[spec.name].nil? or hig[spec.name].version < spec.version then
        hig[spec.name] = spec
      end
    end
  end
  gems_to_update = which_to_update hig, options[:args].uniq
  updated = update_gems gems_to_update
  if updated.empty? then
    say "Nothing to update"
  else
    say "Gems updated: #{updated.map { |spec| spec.name }.join ' '}"
  end
end