# File lib/os.rb, line 31
  def self.posix?
    @posix ||=
    begin
      if OS.windows?
        begin
          begin
            # what if we're on interix...

            # untested, of course

            Process.wait fork{}
            true
          rescue NotImplementedError, NoMethodError
            false
          end
        end
      else
        # assume non windows is posix

        true
      end
    end

  end