diff --git a/command/cli.go b/command/cli.go
index 7b81998a9..02ec5973f 100644
--- a/command/cli.go
+++ b/command/cli.go
@@ -2,11 +2,14 @@ package command
 
 import (
 	"flag"
+	"fmt"
 	"math"
+	"strings"
 
 	"github.com/hashicorp/packer/helper/enumflag"
 	kvflag "github.com/hashicorp/packer/helper/flag-kv"
 	sliceflag "github.com/hashicorp/packer/helper/flag-slice"
+	"github.com/hashicorp/packer/packer"
 )
 
 // NewMetaArgs parses cli args and put possible values
@@ -17,12 +20,38 @@ func (ma *MetaArgs) AddFlagSets(fs *flag.FlagSet) {
 	fs.Var((*kvflag.StringSlice)(&ma.VarFiles), "var-file", "")
 }
 
+// ConfigType tells what type of config we should use, it can return values
+// like "hcl" or "json".
+// Make sure Args was correctly set before.
+func (ma *MetaArgs) ConfigType() (string, error) {
+	switch len(ma.Args) {
+	// TODO(azr): in the future, I want to allow passing multiple arguments to
+	// merge HCL confs together; but this will probably need an RFC first.
+	// TODO(azr): To allow piping HCL2 confs (when args is "-"), we probably
+	// will need to add a setting that says "this is an HCL config".
+	case 1:
+		name := ma.Args[0]
+		if strings.HasSuffix(name, ".pkr.hcl") ||
+			strings.HasSuffix(name, ".pkr.json") {
+			return "hcl", nil
+		}
+		isDir, err := isDir(name)
+		if isDir {
+			return "hcl", err
+		}
+		return "json", err
+	default:
+		return "", fmt.Errorf("packer only takes on argument: %q", ma.Args)
+	}
+}
+
 // MetaArgs defines commonalities between all comands
 type MetaArgs struct {
 	Args         []string
 	Only, Except []string
 	Vars         map[string]string
 	VarFiles     []string
+	Ui           packer.Ui
 }
 
 func (ba *BuildArgs) AddFlagSets(flags *flag.FlagSet) {
@@ -42,6 +71,7 @@ func (ba *BuildArgs) AddFlagSets(flags *flag.FlagSet) {
 
 func (ba *BuildArgs) ParseArgvs(args []string) int {
 	flags := flag.NewFlagSet("build", flag.ContinueOnError)
+	flags.Usage = func() { ba.Ui.Say(ba.Help()) }
 	ba.AddFlagSets(flags)
 	err := flags.Parse(args)
 	if err != nil {
@@ -66,6 +96,7 @@ type BuildArgs struct {
 
 func (ca *ConsoleArgs) ParseArgvs(args []string) int {
 	flags := flag.NewFlagSet("console", flag.ContinueOnError)
+	flags.Usage = func() { ca.Ui.Say(ca.Help()) }
 	ca.AddFlagSets(flags)
 	err := flags.Parse(args)
 	if err != nil {
@@ -86,7 +117,8 @@ func (fa *FixArgs) AddFlagSets(flags *flag.FlagSet) {
 }
 
 func (fa *FixArgs) ParseArgvs(args []string) int {
-	flags := flag.NewFlagSet("build", flag.ContinueOnError)
+	flags := flag.NewFlagSet("fix", flag.ContinueOnError)
+	flags.Usage = func() { fa.Ui.Say(fa.Help()) }
 	fa.AddFlagSets(flags)
 	err := flags.Parse(args)
 	if err != nil {
@@ -110,7 +142,8 @@ func (va *ValidateArgs) AddFlagSets(flags *flag.FlagSet) {
 }
 
 func (va *ValidateArgs) ParseArgvs(args []string) int {
-	flags := flag.NewFlagSet("build", flag.ContinueOnError)
+	flags := flag.NewFlagSet("validate", flag.ContinueOnError)
+	flags.Usage = func() { va.Ui.Say(va.Help()) }
 	va.AddFlagSets(flags)
 	err := flags.Parse(args)
 	if err != nil {