# File lib/chef/mixin/command.rb, line 82
      def not_if(command, args = {})
        if command.kind_of?(Proc)
          chdir_or_tmpdir(args[:cwd]) do
            res = command.call
            if res
              return false
            end
          end
        else  
          status = run_command({:command => command, :ignore_failure => true}.merge(args))
          if status.exitstatus == 0
            return false
          end
        end
        true
      end