require 'socket'

gs = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM, 0)
sockaddr = Socket.sockaddr_in(8080, '0.0.0.0')
gs.bind(sockaddr)
gs.listen(5)

socks = [gs]

loop do
  nsock = select(socks)
  next if nsock == nil
  for s in nsock[0]
    if s == gs
      socks.push(s.accept.first)
      print(s, " is accepted\n")
    else
      if s.eof?
        # nc -vz localhost 1296
        print(s, " is gone\n")
        s.close
        socks.delete(s)
      else
        p :come
        # nc localhost 1296
        # してhoge エンターでおうむ返し
        str = s.gets
        s.write(str)
      end
    end
  end
end