Merge remote-tracking branch 'upstream/master'

Conflicts:
	app.go
	command.go
	flag.go

README.md

@@ -172,6 +172,8 @@ app.Flags = []cli.Flag {
 }
 ```
 
+That flag can then be set with `--lang spanish` or `-l spanish`. Note that giving two different forms of the same flag in the same command invocation is an error.
+
 #### Values from the Environment
 
 You can also have the default value set from the environment via `EnvVar`.  e.g.
@@ -187,7 +189,18 @@ app.Flags = []cli.Flag {
 }
 ```
 
-That flag can then be set with `--lang spanish` or `-l spanish`. Note that giving two different forms of the same flag in the same command invocation is an error.
+The `EnvVar` may also be given as a comma-delimited "cascade", where the first environment variable that resolves is used as the default.
+
+``` go
+app.Flags = []cli.Flag {
+  cli.StringFlag{
+    Name: "lang, l",
+    Value: "english",
+    Usage: "language for the greeting",
+    EnvVar: "LEGACY_COMPAT_LANG,APP_LANG,LANG",
+  },
+}
+```
 
 ### Subcommands
 
@@ -280,6 +293,6 @@ setting the `PROG` variable to the name of your program:
 ## Contribution Guidelines
 Feel free to put up a pull request to fix a bug or maybe add a feature. I will give it a code review and make sure that it does not break backwards compatibility. If I or any other collaborators agree that it is in line with the vision of the project, we will work with you to get the code into a mergeable state and merge it into the master branch.
 
-If you are have contributed something significant to the project, I will most likely add you as a collaborator. As a collaborator you are given the ability to merge others pull requests. It is very important that new code does not break existing code, so be careful about what code you do choose to merge. If you have any questions feel free to link @codegangsta to the issue in question and we can review it together.
+If you have contributed something significant to the project, I will most likely add you as a collaborator. As a collaborator you are given the ability to merge others pull requests. It is very important that new code does not break existing code, so be careful about what code you do choose to merge. If you have any questions feel free to link @codegangsta to the issue in question and we can review it together.
 
 If you feel like you have contributed to the project but have not yet been added as a collaborator, I probably forgot to add you. Hit @codegangsta up over email and we will get it figured out.

app.go

@@ -2,8 +2,11 @@ package cli
 
 import (
 	"fmt"
+	"io"
 	"io/ioutil"
 	"os"
+	"text/tabwriter"
+	"text/template"
 	"time"
 )
 
@@ -31,6 +34,9 @@ type App struct {
 	// An action to execute before any subcommands are run, but after the context is ready
 	// If a non-nil error is returned, no subcommands are run
 	Before func(context *Context) error
+	// An action to execute after any subcommands are run, but after the subcommand has finished
+	// It is run even if Action() panics
+	After func(context *Context) error
 	// The action to execute when no subcommands are specified
 	Action func(context *Context)
 	// Execute this function if the proper command cannot be found
@@ -41,6 +47,8 @@ type App struct {
 	Author string
 	// Author e-mail
 	Email string
+	// Writer writer to write output to
+	Writer io.Writer
 }
 
 // Tries to find out when this binary was compiled.
@@ -62,15 +70,36 @@ func NewApp() *App {
 		BashComplete: DefaultAppComplete,
 		Action:       helpCommand.Action,
 		Compiled:     compileTime(),
+		Author:       "Author",
+		Email:        "unknown@email",
+		Writer:       os.Stdout,
 	}
 }
 
 // Entry point to the cli app. Parses the arguments slice and routes to the proper flag/args combination
-func (a *App) Run(arguments []string) error {
+func (a *App) Run(arguments []string) (err error) {
+	if HelpPrinter == nil {
+		defer func() {
+			HelpPrinter = nil
+		}()
+
+		HelpPrinter = func(templ string, data interface{}) {
+			w := tabwriter.NewWriter(a.Writer, 0, 8, 1, '\t', 0)
+			t := template.Must(template.New("help").Parse(templ))
+			err := t.Execute(w, data)
+			if err != nil {
+				panic(err)
+			}
+			w.Flush()
+		}
+	}
+
 	// append help to commands
 	if a.Command(helpCommand.Name) == nil && !a.HideHelp {
 		a.Commands = append(a.Commands, helpCommand)
-		a.appendFlag(HelpFlag)
+		if (HelpFlag != BoolFlag{}) {
+			a.appendFlag(HelpFlag)
+		}
 	}
 
 	//append version/help flags
@@ -85,7 +114,7 @@ func (a *App) Run(arguments []string) error {
 	// parse flags
 	set := flagSet(a.Name, a.Flags)
 	set.SetOutput(ioutil.Discard)
-	err := set.Parse(arguments[1:])
+	err = set.Parse(arguments[1:])
 	nerr := normalizeFlags(a.Flags, set)
 	cerr := checkRequiredFlags(a.Flags, set)
 
@@ -93,10 +122,10 @@ func (a *App) Run(arguments []string) error {
 
 	// Define here so it closes over the above variables
 	showErrAndHelp := func(err error) {
-		fmt.Println(err)
-		fmt.Println("")
+		fmt.Fprintln(a.Writer, err)
+		fmt.Fprintln(a.Writer)
 		ShowAppHelp(context)
-		fmt.Println("")
+		fmt.Fprintln(a.Writer)
 	}
 
 	if nerr != nil {
@@ -126,6 +155,15 @@ func (a *App) Run(arguments []string) error {
 		return nil
 	}
 
+	if a.After != nil {
+		defer func() {
+			// err is always nil here.
+			// There is a check to see if it is non-nil
+			// just few lines before.
+			err = a.After(context)
+		}()
+	}
+
 	if a.Before != nil {
 		err := a.Before(context)
 		if err != nil {
@@ -150,18 +188,20 @@ func (a *App) Run(arguments []string) error {
 // Another entry point to the cli app, takes care of passing arguments and error handling
 func (a *App) RunAndExitOnError() {
 	if err := a.Run(os.Args); err != nil {
-		os.Stderr.WriteString(fmt.Sprintln(err))
+		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
 	}
 }
 
 // Invokes the subcommand given the context, parses ctx.Args() to generate command-specific flags
-func (a *App) RunAsSubcommand(ctx *Context) error {
+func (a *App) RunAsSubcommand(ctx *Context) (err error) {
 	// append help to commands
 	if len(a.Commands) > 0 {
 		if a.Command(helpCommand.Name) == nil && !a.HideHelp {
 			a.Commands = append(a.Commands, helpCommand)
-			a.appendFlag(HelpFlag)
+			if (HelpFlag != BoolFlag{}) {
+				a.appendFlag(HelpFlag)
+			}
 		}
 	}
 
@@ -173,7 +213,7 @@ func (a *App) RunAsSubcommand(ctx *Context) error {
 	// parse flags
 	set := flagSet(a.Name, a.Flags)
 	set.SetOutput(ioutil.Discard)
-	err := set.Parse(ctx.Args().Tail())
+	err = set.Parse(ctx.Args().Tail())
 	nerr := normalizeFlags(a.Flags, set)
 	cerr := checkRequiredFlags(a.Flags, set)
 
@@ -181,15 +221,14 @@ func (a *App) RunAsSubcommand(ctx *Context) error {
 
 	// Define here so it closes over the above variables
 	showErrAndHelp := func(err error) {
-		fmt.Println(err)
-		fmt.Println("")
+		fmt.Fprintln(a.Writer, err)
+		fmt.Fprintln(a.Writer)
 		if len(a.Commands) > 0 {
 			ShowSubcommandHelp(context)
 		} else {
 			ShowCommandHelp(ctx, context.Args().First())
 		}
-		fmt.Println("")
-
+		fmt.Fprintln(a.Writer, err)
 	}
 
 	if nerr != nil {
@@ -203,8 +242,7 @@ func (a *App) RunAsSubcommand(ctx *Context) error {
 	}
 
 	if err != nil {
-		fmt.Printf("Incorrect Usage.\n\n")
-		ShowSubcommandHelp(context)
+		showErrAndHelp(err)
 		return err
 	}
 
@@ -222,6 +260,15 @@ func (a *App) RunAsSubcommand(ctx *Context) error {
 		}
 	}
 
+	if a.After != nil {
+		defer func() {
+			// err is always nil here.
+			// There is a check to see if it is non-nil
+			// just few lines before.
+			err = a.After(context)
+		}()
+	}
+
 	if a.Before != nil {
 		err := a.Before(context)
 		if err != nil {
@@ -239,11 +286,7 @@ func (a *App) RunAsSubcommand(ctx *Context) error {
 	}
 
 	// Run default Action
-	if len(a.Commands) > 0 {
-		a.Action(context)
-	} else {
-		a.Action(ctx)
-	}
+	a.Action(context)
 
 	return nil
 }

app_test.go

@@ -1,6 +1,7 @@
 package cli_test
 
 import (
+	"flag"
 	"fmt"
 	"os"
 	"testing"
@@ -192,6 +193,76 @@ func TestApp_CommandWithArgBeforeFlags(t *testing.T) {
 	expect(t, firstArg, "my-arg")
 }
 
+func TestApp_RunAsSubcommandParseFlags(t *testing.T) {
+	var context *cli.Context
+
+	a := cli.NewApp()
+	a.Commands = []cli.Command{
+		{
+			Name: "foo",
+			Action: func(c *cli.Context) {
+				context = c
+			},
+			Flags: []cli.Flag{
+				cli.StringFlag{
+					Name:  "lang",
+					Value: "english",
+					Usage: "language for the greeting",
+				},
+			},
+			Before: func(_ *cli.Context) error { return nil },
+		},
+	}
+	a.Run([]string{"", "foo", "--lang", "spanish", "abcd"})
+
+	expect(t, context.Args().Get(0), "abcd")
+	expect(t, context.String("lang"), "spanish")
+}
+
+func TestApp_CommandWithFlagBeforeTerminator(t *testing.T) {
+	var parsedOption string
+	var args []string
+
+	app := cli.NewApp()
+	command := cli.Command{
+		Name: "cmd",
+		Flags: []cli.Flag{
+			cli.StringFlag{Name: "option", Value: "", Usage: "some option"},
+		},
+		Action: func(c *cli.Context) {
+			parsedOption = c.String("option")
+			args = c.Args()
+		},
+	}
+	app.Commands = []cli.Command{command}
+
+	app.Run([]string{"", "cmd", "my-arg", "--option", "my-option", "--", "--notARealFlag"})
+
+	expect(t, parsedOption, "my-option")
+	expect(t, args[0], "my-arg")
+	expect(t, args[1], "--")
+	expect(t, args[2], "--notARealFlag")
+}
+
+func TestApp_CommandWithNoFlagBeforeTerminator(t *testing.T) {
+	var args []string
+
+	app := cli.NewApp()
+	command := cli.Command{
+		Name: "cmd",
+		Action: func(c *cli.Context) {
+			args = c.Args()
+		},
+	}
+	app.Commands = []cli.Command{command}
+
+	app.Run([]string{"", "cmd", "my-arg", "--", "notAFlagAtAll"})
+
+	expect(t, args[0], "my-arg")
+	expect(t, args[1], "--")
+	expect(t, args[2], "notAFlagAtAll")
+}
+
 func TestApp_Float64Flag(t *testing.T) {
 	var meters float64
 
@@ -265,6 +336,50 @@ func TestApp_ParseSliceFlags(t *testing.T) {
 	}
 }
 
+func TestApp_DefaultStdout(t *testing.T) {
+	app := cli.NewApp()
+
+	if app.Writer != os.Stdout {
+		t.Error("Default output writer not set.")
+	}
+}
+
+type mockWriter struct {
+	written []byte
+}
+
+func (fw *mockWriter) Write(p []byte) (n int, err error) {
+	if fw.written == nil {
+		fw.written = p
+	} else {
+		fw.written = append(fw.written, p...)
+	}
+
+	return len(p), nil
+}
+
+func (fw *mockWriter) GetWritten() (b []byte) {
+	return fw.written
+}
+
+func TestApp_SetStdout(t *testing.T) {
+	w := &mockWriter{}
+
+	app := cli.NewApp()
+	app.Name = "test"
+	app.Writer = w
+
+	err := app.Run([]string{"help"})
+
+	if err != nil {
+		t.Fatalf("Run error: %s", err)
+	}
+
+	if len(w.written) == 0 {
+		t.Error("App did not write output to desired writer.")
+	}
+}
+
 func TestApp_BeforeFunc(t *testing.T) {
 	beforeRun, subcommandRun := false, false
 	beforeError := fmt.Errorf("fail")
@@ -331,6 +446,87 @@ func TestApp_BeforeFunc(t *testing.T) {
 
 }
 
+func TestApp_AfterFunc(t *testing.T) {
+	afterRun, subcommandRun := false, false
+	afterError := fmt.Errorf("fail")
+	var err error
+
+	app := cli.NewApp()
+
+	app.After = func(c *cli.Context) error {
+		afterRun = true
+		s := c.String("opt")
+		if s == "fail" {
+			return afterError
+		}
+
+		return nil
+	}
+
+	app.Commands = []cli.Command{
+		cli.Command{
+			Name: "sub",
+			Action: func(c *cli.Context) {
+				subcommandRun = true
+			},
+		},
+	}
+
+	app.Flags = []cli.Flag{
+		cli.StringFlag{Name: "opt"},
+	}
+
+	// run with the After() func succeeding
+	err = app.Run([]string{"command", "--opt", "succeed", "sub"})
+
+	if err != nil {
+		t.Fatalf("Run error: %s", err)
+	}
+
+	if afterRun == false {
+		t.Errorf("After() not executed when expected")
+	}
+
+	if subcommandRun == false {
+		t.Errorf("Subcommand not executed when expected")
+	}
+
+	// reset
+	afterRun, subcommandRun = false, false
+
+	// run with the Before() func failing
+	err = app.Run([]string{"command", "--opt", "fail", "sub"})
+
+	// should be the same error produced by the Before func
+	if err != afterError {
+		t.Errorf("Run error expected, but not received")
+	}
+
+	if afterRun == false {
+		t.Errorf("After() not executed when expected")
+	}
+
+	if subcommandRun == false {
+		t.Errorf("Subcommand not executed when expected")
+	}
+}
+
+func TestAppNoHelpFlag(t *testing.T) {
+	oldFlag := cli.HelpFlag
+	defer func() {
+		cli.HelpFlag = oldFlag
+	}()
+
+	cli.HelpFlag = cli.BoolFlag{}
+
+	app := cli.NewApp()
+	err := app.Run([]string{"test", "-h"})
+
+	if err != flag.ErrHelp {
+		t.Errorf("expected error about missing help flag, but got: %s (%T)", err, err)
+	}
+}
+
 func TestAppHelpPrinter(t *testing.T) {
 	oldPrinter := cli.HelpPrinter
 	defer func() {

command.go

@@ -21,6 +21,9 @@ type Command struct {
 	// An action to execute before any sub-subcommands are run, but after the context is ready
 	// If a non-nil error is returned, no sub-subcommands are run
 	Before func(context *Context) error
+	// An action to execute after any subcommands are run, but after the subcommand has finished
+	// It is run even if Action() panics
+	After func(context *Context) error
 	// The function to call when this command is invoked
 	Action func(context *Context)
 	// List of child commands
@@ -36,11 +39,11 @@ type Command struct {
 // Invokes the command given the context, parses ctx.Args() to generate command-specific flags
 func (c Command) Run(ctx *Context) error {
 
-	if len(c.Subcommands) > 0 || c.Before != nil {
+	if len(c.Subcommands) > 0 || c.Before != nil || c.After != nil {
 		return c.startApp(ctx)
 	}
 
-	if !c.HideHelp {
+	if !c.HideHelp && (HelpFlag != BoolFlag{}) {
 		// append help to flags
 		c.Flags = append(
 			c.Flags,
@@ -56,18 +59,30 @@ func (c Command) Run(ctx *Context) error {
 	set.SetOutput(ioutil.Discard)
 
 	firstFlagIndex := -1
+	terminatorIndex := -1
 	for index, arg := range ctx.Args() {
-		if strings.HasPrefix(arg, "-") {
-			firstFlagIndex = index
+		if arg == "--" {
+			terminatorIndex = index
 			break
+		} else if strings.HasPrefix(arg, "-") && firstFlagIndex == -1 {
+			firstFlagIndex = index
 		}
 	}
 
 	var err error
 	if firstFlagIndex > -1 && !c.SkipFlagParsing {
 		args := ctx.Args()
-		regularArgs := args[1:firstFlagIndex]
-		flagArgs := args[firstFlagIndex:]
+		regularArgs := make([]string, len(args[1:firstFlagIndex]))
+		copy(regularArgs, args[1:firstFlagIndex])
+
+		var flagArgs []string
+		if terminatorIndex > -1 {
+			flagArgs = args[firstFlagIndex:terminatorIndex]
+			regularArgs = append(regularArgs, args[terminatorIndex:]...)
+		} else {
+			flagArgs = args[firstFlagIndex:]
+		}
+
 		err = set.Parse(append(flagArgs, regularArgs...))
 	} else {
 		err = set.Parse(ctx.Args().Tail())
@@ -75,10 +90,10 @@ func (c Command) Run(ctx *Context) error {
 
 	// Define here so it closes over the above variables
 	showErrAndHelp := func(err error) {
-		fmt.Println(err)
-		fmt.Println("")
+		fmt.Fprintln(ctx.App.Writer, err)
+		fmt.Fprintln(ctx.App.Writer)
 		ShowCommandHelp(ctx, c.Name)
-		fmt.Println("")
+		fmt.Fprintln(ctx.App.Writer)
 	}
 
 	if err != nil {
@@ -144,6 +159,7 @@ func (c Command) startApp(ctx *Context) error {
 
 	// set the actions
 	app.Before = c.Before
+	app.After = c.After
 	if c.Action != nil {
 		app.Action = c.Action
 	} else {

flag.go

@@ -21,6 +21,8 @@ var VersionFlag = BoolFlag{
 }
 
 // This flag prints the help for all commands and subcommands
+// Set to the zero value (BoolFlag{}) to disable flag -- keeps subcommand
+// unless HideHelp is set to true)
 var HelpFlag = BoolFlag{
 	Name:  "help, h",
 	Usage: "show help",
@@ -69,15 +71,24 @@ type GenericFlag struct {
 	Required bool
 }
 
+// String returns the string representation of the generic flag to display the
+// help text to the user (uses the String() method of the generic flag to show
+// the value)
 func (f GenericFlag) String() string {
-	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s%s %v\t`%v` %s", prefixFor(f.Name), f.Name, f.Value, "-"+f.Name+" option -"+f.Name+" option", f.Usage))
+	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s%s \"%v\"\t%v", prefixFor(f.Name), f.Name, f.Value, f.Usage))
 }
 
+// Apply takes the flagset and calls Set on the generic flag with the value
+// provided by the user for parsing by the flag
 func (f GenericFlag) Apply(set *flag.FlagSet) {
 	val := f.Value
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
-			val.Set(envVal)
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
+				val.Set(envVal)
+				break
+			}
 		}
 	}
 
@@ -120,17 +131,22 @@ type StringSliceFlag struct {
 func (f StringSliceFlag) String() string {
 	firstName := strings.Trim(strings.Split(f.Name, ",")[0], " ")
 	pref := prefixFor(firstName)
-	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s '%v'\t%v", prefixedNames(f.Name), pref+firstName+" option "+pref+firstName+" option", f.Usage))
+	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s [%v]\t%v", prefixedNames(f.Name), pref+firstName+" option "+pref+firstName+" option", f.Usage))
 }
 
 func (f StringSliceFlag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
-			newVal := &StringSlice{}
-			for _, s := range strings.Split(envVal, ",") {
-				newVal.Set(s)
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
+				newVal := &StringSlice{}
+				for _, s := range strings.Split(envVal, ",") {
+					s = strings.TrimSpace(s)
+					newVal.Set(s)
+				}
+				f.Value = newVal
+				break
 			}
-			f.Value = newVal
 		}
 	}
 
@@ -179,20 +195,25 @@ type IntSliceFlag struct {
 func (f IntSliceFlag) String() string {
 	firstName := strings.Trim(strings.Split(f.Name, ",")[0], " ")
 	pref := prefixFor(firstName)
-	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s '%v'\t%v", prefixedNames(f.Name), pref+firstName+" option "+pref+firstName+" option", f.Usage))
+	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s [%v]\t%v", prefixedNames(f.Name), pref+firstName+" option "+pref+firstName+" option", f.Usage))
 }
 
 func (f IntSliceFlag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
-			newVal := &IntSlice{}
-			for _, s := range strings.Split(envVal, ",") {
-				err := newVal.Set(s)
-				if err != nil {
-					fmt.Fprintf(os.Stderr, err.Error())
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
+				newVal := &IntSlice{}
+				for _, s := range strings.Split(envVal, ",") {
+					s = strings.TrimSpace(s)
+					err := newVal.Set(s)
+					if err != nil {
+						fmt.Fprintf(os.Stderr, err.Error())
+					}
 				}
+				f.Value = newVal
+				break
 			}
-			f.Value = newVal
 		}
 	}
 
@@ -223,10 +244,14 @@ func (f BoolFlag) String() string {
 func (f BoolFlag) Apply(set *flag.FlagSet) {
 	val := false
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
-			envValBool, err := strconv.ParseBool(envVal)
-			if err == nil {
-				val = envValBool
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
+				envValBool, err := strconv.ParseBool(envVal)
+				if err == nil {
+					val = envValBool
+				}
+				break
 			}
 		}
 	}
@@ -258,10 +283,14 @@ func (f BoolTFlag) String() string {
 func (f BoolTFlag) Apply(set *flag.FlagSet) {
 	val := true
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
-			envValBool, err := strconv.ParseBool(envVal)
-			if err == nil {
-				val = envValBool
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
+				envValBool, err := strconv.ParseBool(envVal)
+				if err == nil {
+					val = envValBool
+					break
+				}
 			}
 		}
 	}
@@ -292,7 +321,7 @@ func (f StringFlag) String() string {
 	fmtString = "%s %v\t%v"
 
 	if len(f.Value) > 0 {
-		fmtString = "%s '%v'\t%v"
+		fmtString = "%s \"%v\"\t%v"
 	} else {
 		fmtString = "%s %v\t%v"
 	}
@@ -302,8 +331,12 @@ func (f StringFlag) String() string {
 
 func (f StringFlag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
-			f.Value = envVal
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
+				f.Value = envVal
+				break
+			}
 		}
 	}
 
@@ -329,15 +362,19 @@ type IntFlag struct {
 }
 
 func (f IntFlag) String() string {
-	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s '%v'\t%v", prefixedNames(f.Name), f.Value, f.Usage))
+	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s \"%v\"\t%v", prefixedNames(f.Name), f.Value, f.Usage))
 }
 
 func (f IntFlag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
-			envValInt, err := strconv.ParseUint(envVal, 10, 64)
-			if err == nil {
-				f.Value = int(envValInt)
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
+				envValInt, err := strconv.ParseInt(envVal, 0, 64)
+				if err == nil {
+					f.Value = int(envValInt)
+					break
+				}
 			}
 		}
 	}
@@ -364,15 +401,19 @@ type DurationFlag struct {
 }
 
 func (f DurationFlag) String() string {
-	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s '%v'\t%v", prefixedNames(f.Name), f.Value, f.Usage))
+	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s \"%v\"\t%v", prefixedNames(f.Name), f.Value, f.Usage))
 }
 
 func (f DurationFlag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
-			envValDuration, err := time.ParseDuration(envVal)
-			if err == nil {
-				f.Value = envValDuration
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
+				envValDuration, err := time.ParseDuration(envVal)
+				if err == nil {
+					f.Value = envValDuration
+					break
+				}
 			}
 		}
 	}
@@ -399,15 +440,18 @@ type Float64Flag struct {
 }
 
 func (f Float64Flag) String() string {
-	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s '%v'\t%v", prefixedNames(f.Name), f.Value, f.Usage))
+	return withHints(f.EnvVar, f.Required, fmt.Sprintf("%s \"%v\"\t%v", prefixedNames(f.Name), f.Value, f.Usage))
 }
 
 func (f Float64Flag) Apply(set *flag.FlagSet) {
 	if f.EnvVar != "" {
-		if envVal := os.Getenv(f.EnvVar); envVal != "" {
-			envValFloat, err := strconv.ParseFloat(envVal, 10)
-			if err == nil {
-				f.Value = float64(envValFloat)
+		for _, envVar := range strings.Split(f.EnvVar, ",") {
+			envVar = strings.TrimSpace(envVar)
+			if envVal := os.Getenv(envVar); envVal != "" {
+				envValFloat, err := strconv.ParseFloat(envVal, 10)
+				if err == nil {
+					f.Value = float64(envValFloat)
+				}
 			}
 		}
 	}
@@ -450,7 +494,7 @@ func prefixedNames(fullName string) (prefixed string) {
 func withEnvHint(envVar, str string) string {
 	envText := ""
 	if envVar != "" {
-		envText = fmt.Sprintf(" [$%s]", envVar)
+		envText = fmt.Sprintf(" [$%s]", strings.Join(strings.Split(envVar, ","), ", $"))
 	}
 	return str + envText
 }

flag_test.go

@@ -38,7 +38,7 @@ var stringFlagTests = []struct {
 	{"help", "", "--help \t"},
 	{"h", "", "-h \t"},
 	{"h", "", "-h \t"},
-	{"test", "Something", "--test 'Something'\t"},
+	{"test", "Something", "--test \"Something\"\t"},
 }
 
 func TestStringFlagHelpOutput(t *testing.T) {
@@ -54,7 +54,7 @@ func TestStringFlagHelpOutput(t *testing.T) {
 }
 
 func TestStringFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_FOO", "derp")
 	for _, test := range stringFlagTests {
 		flag := cli.StringFlag{Name: test.name, Value: test.value, EnvVar: "APP_FOO"}
@@ -75,22 +75,22 @@ var stringSliceFlagTests = []struct {
 		s := &cli.StringSlice{}
 		s.Set("")
 		return s
-	}(), "--help '--help option --help option'\t"},
+	}(), "--help [--help option --help option]\t"},
 	{"h", func() *cli.StringSlice {
 		s := &cli.StringSlice{}
 		s.Set("")
 		return s
-	}(), "-h '-h option -h option'\t"},
+	}(), "-h [-h option -h option]\t"},
 	{"h", func() *cli.StringSlice {
 		s := &cli.StringSlice{}
 		s.Set("")
 		return s
-	}(), "-h '-h option -h option'\t"},
+	}(), "-h [-h option -h option]\t"},
 	{"test", func() *cli.StringSlice {
 		s := &cli.StringSlice{}
 		s.Set("Something")
 		return s
-	}(), "--test '--test option --test option'\t"},
+	}(), "--test [--test option --test option]\t"},
 }
 
 func TestStringSliceFlagHelpOutput(t *testing.T) {
@@ -106,7 +106,7 @@ func TestStringSliceFlagHelpOutput(t *testing.T) {
 }
 
 func TestStringSliceFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_QWWX", "11,4")
 	for _, test := range stringSliceFlagTests {
 		flag := cli.StringSliceFlag{Name: test.name, Value: test.value, EnvVar: "APP_QWWX"}
@@ -122,8 +122,8 @@ var intFlagTests = []struct {
 	name     string
 	expected string
 }{
-	{"help", "--help '0'\t"},
-	{"h", "-h '0'\t"},
+	{"help", "--help \"0\"\t"},
+	{"h", "-h \"0\"\t"},
 }
 
 func TestIntFlagHelpOutput(t *testing.T) {
@@ -139,7 +139,7 @@ func TestIntFlagHelpOutput(t *testing.T) {
 }
 
 func TestIntFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_BAR", "2")
 	for _, test := range intFlagTests {
 		flag := cli.IntFlag{Name: test.name, EnvVar: "APP_BAR"}
@@ -155,8 +155,8 @@ var durationFlagTests = []struct {
 	name     string
 	expected string
 }{
-	{"help", "--help '0'\t"},
-	{"h", "-h '0'\t"},
+	{"help", "--help \"0\"\t"},
+	{"h", "-h \"0\"\t"},
 }
 
 func TestDurationFlagHelpOutput(t *testing.T) {
@@ -172,7 +172,7 @@ func TestDurationFlagHelpOutput(t *testing.T) {
 }
 
 func TestDurationFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_BAR", "2h3m6s")
 	for _, test := range durationFlagTests {
 		flag := cli.DurationFlag{Name: test.name, EnvVar: "APP_BAR"}
@@ -189,14 +189,14 @@ var intSliceFlagTests = []struct {
 	value    *cli.IntSlice
 	expected string
 }{
-	{"help", &cli.IntSlice{}, "--help '--help option --help option'\t"},
-	{"h", &cli.IntSlice{}, "-h '-h option -h option'\t"},
-	{"h", &cli.IntSlice{}, "-h '-h option -h option'\t"},
+	{"help", &cli.IntSlice{}, "--help [--help option --help option]\t"},
+	{"h", &cli.IntSlice{}, "-h [-h option -h option]\t"},
+	{"h", &cli.IntSlice{}, "-h [-h option -h option]\t"},
 	{"test", func() *cli.IntSlice {
 		i := &cli.IntSlice{}
 		i.Set("9")
 		return i
-	}(), "--test '--test option --test option'\t"},
+	}(), "--test [--test option --test option]\t"},
 }
 
 func TestIntSliceFlagHelpOutput(t *testing.T) {
@@ -212,7 +212,7 @@ func TestIntSliceFlagHelpOutput(t *testing.T) {
 }
 
 func TestIntSliceFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_SMURF", "42,3")
 	for _, test := range intSliceFlagTests {
 		flag := cli.IntSliceFlag{Name: test.name, Value: test.value, EnvVar: "APP_SMURF"}
@@ -228,8 +228,8 @@ var float64FlagTests = []struct {
 	name     string
 	expected string
 }{
-	{"help", "--help '0'\t"},
-	{"h", "-h '0'\t"},
+	{"help", "--help \"0\"\t"},
+	{"h", "-h \"0\"\t"},
 }
 
 func TestFloat64FlagHelpOutput(t *testing.T) {
@@ -245,7 +245,7 @@ func TestFloat64FlagHelpOutput(t *testing.T) {
 }
 
 func TestFloat64FlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_BAZ", "99.4")
 	for _, test := range float64FlagTests {
 		flag := cli.Float64Flag{Name: test.name, EnvVar: "APP_BAZ"}
@@ -262,15 +262,14 @@ var genericFlagTests = []struct {
 	value    cli.Generic
 	expected string
 }{
-	{"help", &Parser{}, "--help <nil>\t`-help option -help option` "},
-	{"h", &Parser{}, "-h <nil>\t`-h option -h option` "},
-	{"test", &Parser{}, "--test <nil>\t`-test option -test option` "},
+	{"test", &Parser{"abc", "def"}, "--test \"abc,def\"\ttest flag"},
+	{"t", &Parser{"abc", "def"}, "-t \"abc,def\"\ttest flag"},
 }
 
 func TestGenericFlagHelpOutput(t *testing.T) {
 
 	for _, test := range genericFlagTests {
-		flag := cli.GenericFlag{Name: test.name}
+		flag := cli.GenericFlag{Name: test.name, Value: test.value, Usage: "test flag"}
 		output := flag.String()
 
 		if output != test.expected {
@@ -280,7 +279,7 @@ func TestGenericFlagHelpOutput(t *testing.T) {
 }
 
 func TestGenericFlagWithEnvVarHelpOutput(t *testing.T) {
-
+	os.Clearenv()
 	os.Setenv("APP_ZAP", "3")
 	for _, test := range genericFlagTests {
 		flag := cli.GenericFlag{Name: test.name, EnvVar: "APP_ZAP"}
@@ -309,6 +308,7 @@ func TestParseMultiString(t *testing.T) {
 }
 
 func TestParseMultiStringFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_COUNT", "20")
 	(&cli.App{
 		Flags: []cli.Flag{
@@ -325,6 +325,24 @@ func TestParseMultiStringFromEnv(t *testing.T) {
 	}).Run([]string{"run"})
 }
 
+func TestParseMultiStringFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_COUNT", "20")
+	(&cli.App{
+		Flags: []cli.Flag{
+			cli.StringFlag{Name: "count, c", EnvVar: "COMPAT_COUNT,APP_COUNT"},
+		},
+		Action: func(ctx *cli.Context) {
+			if ctx.String("count") != "20" {
+				t.Errorf("main name not set")
+			}
+			if ctx.String("c") != "20" {
+				t.Errorf("short name not set")
+			}
+		},
+	}).Run([]string{"run"})
+}
+
 func TestParseMultiStringSlice(t *testing.T) {
 	(&cli.App{
 		Flags: []cli.Flag{
@@ -342,6 +360,7 @@ func TestParseMultiStringSlice(t *testing.T) {
 }
 
 func TestParseMultiStringSliceFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_INTERVALS", "20,30,40")
 
 	(&cli.App{
@@ -359,6 +378,25 @@ func TestParseMultiStringSliceFromEnv(t *testing.T) {
 	}).Run([]string{"run"})
 }
 
+func TestParseMultiStringSliceFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_INTERVALS", "20,30,40")
+
+	(&cli.App{
+		Flags: []cli.Flag{
+			cli.StringSliceFlag{Name: "intervals, i", Value: &cli.StringSlice{}, EnvVar: "COMPAT_INTERVALS,APP_INTERVALS"},
+		},
+		Action: func(ctx *cli.Context) {
+			if !reflect.DeepEqual(ctx.StringSlice("intervals"), []string{"20", "30", "40"}) {
+				t.Errorf("main name not set from env")
+			}
+			if !reflect.DeepEqual(ctx.StringSlice("i"), []string{"20", "30", "40"}) {
+				t.Errorf("short name not set from env")
+			}
+		},
+	}).Run([]string{"run"})
+}
+
 func TestParseMultiInt(t *testing.T) {
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -377,6 +415,7 @@ func TestParseMultiInt(t *testing.T) {
 }
 
 func TestParseMultiIntFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_TIMEOUT_SECONDS", "10")
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -394,6 +433,25 @@ func TestParseMultiIntFromEnv(t *testing.T) {
 	a.Run([]string{"run"})
 }
 
+func TestParseMultiIntFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_TIMEOUT_SECONDS", "10")
+	a := cli.App{
+		Flags: []cli.Flag{
+			cli.IntFlag{Name: "timeout, t", EnvVar: "COMPAT_TIMEOUT_SECONDS,APP_TIMEOUT_SECONDS"},
+		},
+		Action: func(ctx *cli.Context) {
+			if ctx.Int("timeout") != 10 {
+				t.Errorf("main name not set")
+			}
+			if ctx.Int("t") != 10 {
+				t.Errorf("short name not set")
+			}
+		},
+	}
+	a.Run([]string{"run"})
+}
+
 func TestParseMultiIntSlice(t *testing.T) {
 	(&cli.App{
 		Flags: []cli.Flag{
@@ -411,6 +469,7 @@ func TestParseMultiIntSlice(t *testing.T) {
 }
 
 func TestParseMultiIntSliceFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_INTERVALS", "20,30,40")
 
 	(&cli.App{
@@ -428,6 +487,25 @@ func TestParseMultiIntSliceFromEnv(t *testing.T) {
 	}).Run([]string{"run"})
 }
 
+func TestParseMultiIntSliceFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_INTERVALS", "20,30,40")
+
+	(&cli.App{
+		Flags: []cli.Flag{
+			cli.IntSliceFlag{Name: "intervals, i", Value: &cli.IntSlice{}, EnvVar: "COMPAT_INTERVALS,APP_INTERVALS"},
+		},
+		Action: func(ctx *cli.Context) {
+			if !reflect.DeepEqual(ctx.IntSlice("intervals"), []int{20, 30, 40}) {
+				t.Errorf("main name not set from env")
+			}
+			if !reflect.DeepEqual(ctx.IntSlice("i"), []int{20, 30, 40}) {
+				t.Errorf("short name not set from env")
+			}
+		},
+	}).Run([]string{"run"})
+}
+
 func TestParseMultiFloat64(t *testing.T) {
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -446,6 +524,7 @@ func TestParseMultiFloat64(t *testing.T) {
 }
 
 func TestParseMultiFloat64FromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_TIMEOUT_SECONDS", "15.5")
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -463,6 +542,25 @@ func TestParseMultiFloat64FromEnv(t *testing.T) {
 	a.Run([]string{"run"})
 }
 
+func TestParseMultiFloat64FromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_TIMEOUT_SECONDS", "15.5")
+	a := cli.App{
+		Flags: []cli.Flag{
+			cli.Float64Flag{Name: "timeout, t", EnvVar: "COMPAT_TIMEOUT_SECONDS,APP_TIMEOUT_SECONDS"},
+		},
+		Action: func(ctx *cli.Context) {
+			if ctx.Float64("timeout") != 15.5 {
+				t.Errorf("main name not set")
+			}
+			if ctx.Float64("t") != 15.5 {
+				t.Errorf("short name not set")
+			}
+		},
+	}
+	a.Run([]string{"run"})
+}
+
 func TestParseMultiBool(t *testing.T) {
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -481,6 +579,7 @@ func TestParseMultiBool(t *testing.T) {
 }
 
 func TestParseMultiBoolFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_DEBUG", "1")
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -498,6 +597,25 @@ func TestParseMultiBoolFromEnv(t *testing.T) {
 	a.Run([]string{"run"})
 }
 
+func TestParseMultiBoolFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_DEBUG", "1")
+	a := cli.App{
+		Flags: []cli.Flag{
+			cli.BoolFlag{Name: "debug, d", EnvVar: "COMPAT_DEBUG,APP_DEBUG"},
+		},
+		Action: func(ctx *cli.Context) {
+			if ctx.Bool("debug") != true {
+				t.Errorf("main name not set from env")
+			}
+			if ctx.Bool("d") != true {
+				t.Errorf("short name not set from env")
+			}
+		},
+	}
+	a.Run([]string{"run"})
+}
+
 func TestParseMultiBoolT(t *testing.T) {
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -516,6 +634,7 @@ func TestParseMultiBoolT(t *testing.T) {
 }
 
 func TestParseMultiBoolTFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_DEBUG", "0")
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -533,6 +652,25 @@ func TestParseMultiBoolTFromEnv(t *testing.T) {
 	a.Run([]string{"run"})
 }
 
+func TestParseMultiBoolTFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_DEBUG", "0")
+	a := cli.App{
+		Flags: []cli.Flag{
+			cli.BoolTFlag{Name: "debug, d", EnvVar: "COMPAT_DEBUG,APP_DEBUG"},
+		},
+		Action: func(ctx *cli.Context) {
+			if ctx.BoolT("debug") != false {
+				t.Errorf("main name not set from env")
+			}
+			if ctx.BoolT("d") != false {
+				t.Errorf("short name not set from env")
+			}
+		},
+	}
+	a.Run([]string{"run"})
+}
+
 type Parser [2]string
 
 func (p *Parser) Set(value string) error {
@@ -569,6 +707,7 @@ func TestParseGeneric(t *testing.T) {
 }
 
 func TestParseGenericFromEnv(t *testing.T) {
+	os.Clearenv()
 	os.Setenv("APP_SERVE", "20,30")
 	a := cli.App{
 		Flags: []cli.Flag{
@@ -585,3 +724,19 @@ func TestParseGenericFromEnv(t *testing.T) {
 	}
 	a.Run([]string{"run"})
 }
+
+func TestParseGenericFromEnvCascade(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("APP_FOO", "99,2000")
+	a := cli.App{
+		Flags: []cli.Flag{
+			cli.GenericFlag{Name: "foos", Value: &Parser{}, EnvVar: "COMPAT_FOO,APP_FOO"},
+		},
+		Action: func(ctx *cli.Context) {
+			if !reflect.DeepEqual(ctx.Generic("foos"), &Parser{"99", "2000"}) {
+				t.Errorf("value not set from env")
+			}
+		},
+	}
+	a.Run([]string{"run"})
+}

help.go

@@ -1,11 +1,6 @@
 package cli
 
-import (
-	"fmt"
-	"os"
-	"text/tabwriter"
-	"text/template"
-)
+import "fmt"
 
 // The text template for the Default help topic.
 // cli.go uses text/template to render templates. You can
@@ -94,7 +89,9 @@ var helpSubcommand = Command{
 }
 
 // Prints help for the App
-var HelpPrinter = printHelp
+type helpPrinter func(templ string, data interface{})
+
+var HelpPrinter helpPrinter = nil
 
 // Prints version for the App
 var VersionPrinter = printVersion
@@ -106,9 +103,9 @@ func ShowAppHelp(c *Context) {
 // Prints the list of subcommands as the default app completion method
 func DefaultAppComplete(c *Context) {
 	for _, command := range c.App.Commands {
-		fmt.Println(command.Name)
+		fmt.Fprintln(c.App.Writer, command.Name)
 		if command.ShortName != "" {
-			fmt.Println(command.ShortName)
+			fmt.Fprintln(c.App.Writer, command.ShortName)
 		}
 	}
 }
@@ -125,13 +122,13 @@ func ShowCommandHelp(c *Context, command string) {
 	if c.App.CommandNotFound != nil {
 		c.App.CommandNotFound(c, command)
 	} else {
-		fmt.Printf("No help topic for '%v'\n", command)
+		fmt.Fprintf(c.App.Writer, "No help topic for '%v'\n", command)
 	}
 }
 
 // Prints help for the given subcommand
 func ShowSubcommandHelp(c *Context) {
-	HelpPrinter(SubcommandHelpTemplate, c.App)
+	ShowCommandHelp(c, c.Command.Name)
 }
 
 // Prints the version number of the App
@@ -140,7 +137,7 @@ func ShowVersion(c *Context) {
 }
 
 func printVersion(c *Context) {
-	fmt.Printf("%v version %v\n", c.App.Name, c.App.Version)
+	fmt.Fprintf(c.App.Writer, "%v version %v\n", c.App.Name, c.App.Version)
 }
 
 // Prints the lists of commands within a given context
@@ -159,16 +156,6 @@ func ShowCommandCompletions(ctx *Context, command string) {
 	}
 }
 
-func printHelp(templ string, data interface{}) {
-	w := tabwriter.NewWriter(os.Stdout, 0, 8, 1, '\t', 0)
-	t := template.Must(template.New("help").Parse(templ))
-	err := t.Execute(w, data)
-	if err != nil {
-		panic(err)
-	}
-	w.Flush()
-}
-
 func checkVersion(c *Context) bool {
 	if c.GlobalBool("version") {
 		ShowVersion(c)