@@ -5,6 +5,7 @@ import (

 	"bytes"

 	"encoding/base64"

 	"encoding/json"

+	"errors"

 	"fmt"

 	"io"

 	"io/ioutil"

@@ -2411,7 +2412,10 @@ func (cli *DockerCli) CmdSave(args ...string) error {

 		if err != nil {

 			return err

 		}

+	} else if cli.isTerminalOut {

+		return errors.New("Cowardly refusing to save to a terminal. Use the -o flag or redirect.")

 	}

+

 	if len(cmd.Args()) == 1 {

 		image := cmd.Arg(0)

 		if err := cli.stream("GET", "/images/"+image+"/get", nil, output, nil); err != nil {

@@ -1,6 +1,7 @@

 package main

 import (

+	"bytes"

 	"fmt"

 	"io/ioutil"

 	"os"

@@ -8,6 +9,8 @@ import (

 	"path/filepath"

 	"reflect"

 	"testing"

+

+	"github.com/docker/docker/vendor/src/github.com/kr/pty"

 )

 // save a repo and try to load it using stdout

@@ -70,6 +73,34 @@ func TestSaveAndLoadRepoStdout(t *testing.T) {

 	logDone("save - save a repo using stdout")

 	logDone("load - load a repo using stdout")

+

+	pty, tty, err := pty.Open()

+	if err != nil {

+		t.Fatalf("Could not open pty: %v", err)

+	}

+	cmd := exec.Command(dockerBinary, "save", repoName)

+	cmd.Stdin = tty

+	cmd.Stdout = tty

+	cmd.Stderr = tty

+	if err := cmd.Start(); err != nil {

+		t.Fatalf("start err: %v", err)

+	}

+	if err := cmd.Wait(); err == nil {

+		t.Fatal("did not break writing to a TTY")

+	}

+

+	buf := make([]byte, 1024)

+

+	n, err := pty.Read(buf)

+	if err != nil {

+		t.Fatal("could not read tty output")

+	}

+

+	if !bytes.Contains(buf[:n], []byte("Cowardly refusing")) {

+		t.Fatal("help output is not being yielded", out)

+	}

+

+	logDone("save - do not save to a tty")

 }

 func TestSaveSingleTag(t *testing.T) {