Ruby I/O - capturing output of a subprocess on separate stdout and stderr descriptors

gistfile1.txt

## (No Warranty)

class SHFrob02
  def self.runfrob()
    out_rd, out_wr = IO.pipe
    err_rd, err_wr = IO.pipe

    subpid = Process.spawn("ls -d /frob /etc", :in => :close, :out => out_wr, :err => err_wr )       

    samepid, status = Process.wait2(subpid)

    puts status

    out = IO.new(out_rd.to_i, "r")
    err = IO.new(err_rd.to_i, "r")

    out_wr.close
    err_wr.close

    out.each_line do |txt|
      puts "Out: #{txt}"
    end
    
    err.each_line do |txt| 
      puts "Err: #{txt}" 
    end

    return status

  ensure 

    ## NB fails (EBADF) during close
    # out.closed? || out.close
    # err.closed? || err.close

    out_wr.close
    err_wr.close
    
    out_rd.close
    err_rd.close
    
  end
end