# File lib/chef/knife/cookbook_site_install.rb, line 124
      def parse_name_args!
        if name_args.empty?
          ui.error("Please specify a cookbook to download and install.")
          exit 1
        elsif name_args.size >= 2
          unless name_args.last.match(/^(\d+)(\.\d+){1,2}$/) and name_args.size == 2
            ui.error("Installing multiple cookbooks at once is not supported.")
            exit 1
          end
        end
        name_args.first
      end