Re-enabled help for run command and added client-side error messages when arguments are missing

commands.go

@@ -814,14 +814,16 @@ func (srv *Server) CmdTag(stdin io.ReadCloser, stdout io.Writer, args ...string)
 }
 
 func (srv *Server) CmdRun(stdin io.ReadCloser, stdout io.Writer, args ...string) error {
-	config, err := ParseRun(args)
+	config, err := ParseRun(args, stdout)
 	if err != nil {
 		return err
 	}
 	if config.Image == "" {
+		fmt.Fprintln(stdout, "Error: Image not specified")
 		return fmt.Errorf("Image not specified")
 	}
 	if len(config.Cmd) == 0 {
+		fmt.Fprintln(stdout, "Error: Command not specified")
 		return fmt.Errorf("Command not specified")
 	}
 	// Create new container

container.go

@@ -3,8 +3,8 @@ package docker
 import (
 	"encoding/json"
 	"errors"
-	"flag"
 	"fmt"
+	"github.com/dotcloud/docker/rcli"
 	"github.com/kr/pty"
 	"io"
 	"io/ioutil"
@@ -60,9 +60,12 @@ type Config struct {
 	Image      string // Name of the image as it was passed by the operator (eg. could be symbolic)
 }
 
-func ParseRun(args []string) (*Config, error) {
-	cmd := flag.NewFlagSet("", flag.ContinueOnError)
-	cmd.SetOutput(ioutil.Discard)
+func ParseRun(args []string, stdout io.Writer) (*Config, error) {
+	cmd := rcli.Subcmd(stdout, "run", "[OPTIONS] IMAGE COMMAND [ARG...]", "Run a command in a new container")
+	if len(args) > 0 && args[0] != "--help" {
+		cmd.SetOutput(ioutil.Discard)
+	}
+
 	fl_user := cmd.String("u", "", "Username or UID")
 	fl_detach := cmd.Bool("d", false, "Detached mode: leave the container running in the background")
 	fl_stdin := cmd.Bool("i", false, "Keep stdin open even if not attached")