# File lib/rdoc/ri/driver.rb, line 1148
  def setup_pager
    return if @use_stdout

    pagers = [ENV['RI_PAGER'], ENV['PAGER'], 'pager', 'less', 'more']

    pagers.compact.uniq.each do |pager|
      next unless pager

      pager_cmd = pager.split.first

      next unless in_path? pager_cmd

      io = IO.popen(pager, 'w') rescue next

      next if $? and $?.exited? # pager didn't work

      @paging = true

      return io
    end

    @use_stdout = true

    nil
  end