How to exclude the command lines from obtaining stdout through client.ContainerAttach?

[ssppest]

for example:

	resp, err := cli.ContainerCreate(ctx, &container.Config{
		AttachStderr: true,
		AttachStdin:  true,
		Tty:          true,
		AttachStdout: true,
		OpenStdin:    true,
		Cmd:          []string{"/bin/sh"},
		Image:        "alpine",
		WorkingDir:   workingDir,
	},
	if err := cli.ContainerStart(ctx, resp.ID, types.ContainerStartOptions{}); err != nil {
		panic(err)
	}
	attachResp, err := cli.ContainerAttach(ctx, resp.ID, types.ContainerAttachOptions{
		Stderr: true,
		Stdout: true,
		Stdin:  true,
		Stream: true,
	})
	go io.Copy(os.Stdout, waiter.Reader)
	go io.Copy(os.Stderr, waiter.Reader)
	_, err = attachResp.Conn.Write([]byte("ls\r"))
	if err != nil {
		fmt.Println(err)
	}

It will print the command "ls " at first
How to set the option to not use this line and only obtain a simple stdout?