Migrate to cobra CLI

We intend to migrate to the cobra cli from urfave/cli because the
project is more well maintained.  There are also some technical reasons
as well which extend into our remote client work.

Signed-off-by: baude <bbaude@redhat.com>

1 files changed, 1517 insertions, 0 deletions

diff --git a/vendor/github.com/spf13/cobra/command.go b/vendor/github.com/spf13/cobra/command.go
new file mode 100644
index 000000000..34d1bf367
--- /dev/null
+++ b/vendor/github.com/spf13/cobra/command.go
@@ -0,0 +1,1517 @@
+// Copyright © 2013 Steve Francia <spf@spf13.com>.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package cobra is a commander providing a simple interface to create powerful modern CLI interfaces.
+// In addition to providing an interface, Cobra simultaneously provides a controller to organize your application code.
+package cobra
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	flag "github.com/spf13/pflag"
+)
+
+// FParseErrWhitelist configures Flag parse errors to be ignored
+type FParseErrWhitelist flag.ParseErrorsWhitelist
+
+// Command is just that, a command for your application.
+// E.g.  'go run ...' - 'run' is the command. Cobra requires
+// you to define the usage and description as part of your command
+// definition to ensure usability.
+type Command struct {
+	// Use is the one-line usage message.
+	Use string
+
+	// Aliases is an array of aliases that can be used instead of the first word in Use.
+	Aliases []string
+
+	// SuggestFor is an array of command names for which this command will be suggested -
+	// similar to aliases but only suggests.
+	SuggestFor []string
+
+	// Short is the short description shown in the 'help' output.
+	Short string
+
+	// Long is the long message shown in the 'help <this-command>' output.
+	Long string
+
+	// Example is examples of how to use the command.
+	Example string
+
+	// ValidArgs is list of all valid non-flag arguments that are accepted in bash completions
+	ValidArgs []string
+
+	// Expected arguments
+	Args PositionalArgs
+
+	// ArgAliases is List of aliases for ValidArgs.
+	// These are not suggested to the user in the bash completion,
+	// but accepted if entered manually.
+	ArgAliases []string
+
+	// BashCompletionFunction is custom functions used by the bash autocompletion generator.
+	BashCompletionFunction string
+
+	// Deprecated defines, if this command is deprecated and should print this string when used.
+	Deprecated string
+
+	// Hidden defines, if this command is hidden and should NOT show up in the list of available commands.
+	Hidden bool
+
+	// Annotations are key/value pairs that can be used by applications to identify or
+	// group commands.
+	Annotations map[string]string
+
+	// Version defines the version for this command. If this value is non-empty and the command does not
+	// define a "version" flag, a "version" boolean flag will be added to the command and, if specified,
+	// will print content of the "Version" variable.
+	Version string
+
+	// The *Run functions are executed in the following order:
+	//   * PersistentPreRun()
+	//   * PreRun()
+	//   * Run()
+	//   * PostRun()
+	//   * PersistentPostRun()
+	// All functions get the same args, the arguments after the command name.
+	//
+	// PersistentPreRun: children of this command will inherit and execute.
+	PersistentPreRun func(cmd *Command, args []string)
+	// PersistentPreRunE: PersistentPreRun but returns an error.
+	PersistentPreRunE func(cmd *Command, args []string) error
+	// PreRun: children of this command will not inherit.
+	PreRun func(cmd *Command, args []string)
+	// PreRunE: PreRun but returns an error.
+	PreRunE func(cmd *Command, args []string) error
+	// Run: Typically the actual work function. Most commands will only implement this.
+	Run func(cmd *Command, args []string)
+	// RunE: Run but returns an error.
+	RunE func(cmd *Command, args []string) error
+	// PostRun: run after the Run command.
+	PostRun func(cmd *Command, args []string)
+	// PostRunE: PostRun but returns an error.
+	PostRunE func(cmd *Command, args []string) error
+	// PersistentPostRun: children of this command will inherit and execute after PostRun.
+	PersistentPostRun func(cmd *Command, args []string)
+	// PersistentPostRunE: PersistentPostRun but returns an error.
+	PersistentPostRunE func(cmd *Command, args []string) error
+
+	// SilenceErrors is an option to quiet errors down stream.
+	SilenceErrors bool
+
+	// SilenceUsage is an option to silence usage when an error occurs.
+	SilenceUsage bool
+
+	// DisableFlagParsing disables the flag parsing.
+	// If this is true all flags will be passed to the command as arguments.
+	DisableFlagParsing bool
+
+	// DisableAutoGenTag defines, if gen tag ("Auto generated by spf13/cobra...")
+	// will be printed by generating docs for this command.
+	DisableAutoGenTag bool
+
+	// DisableFlagsInUseLine will disable the addition of [flags] to the usage
+	// line of a command when printing help or generating docs
+	DisableFlagsInUseLine bool
+
+	// DisableSuggestions disables the suggestions based on Levenshtein distance
+	// that go along with 'unknown command' messages.
+	DisableSuggestions bool
+	// SuggestionsMinimumDistance defines minimum levenshtein distance to display suggestions.
+	// Must be > 0.
+	SuggestionsMinimumDistance int
+
+	// TraverseChildren parses flags on all parents before executing child command.
+	TraverseChildren bool
+
+	//FParseErrWhitelist flag parse errors to be ignored
+	FParseErrWhitelist FParseErrWhitelist
+
+	// commands is the list of commands supported by this program.
+	commands []*Command
+	// parent is a parent command for this command.
+	parent *Command
+	// Max lengths of commands' string lengths for use in padding.
+	commandsMaxUseLen         int
+	commandsMaxCommandPathLen int
+	commandsMaxNameLen        int
+	// commandsAreSorted defines, if command slice are sorted or not.
+	commandsAreSorted bool
+	// commandCalledAs is the name or alias value used to call this command.
+	commandCalledAs struct {
+		name   string
+		called bool
+	}
+
+	// args is actual args parsed from flags.
+	args []string
+	// flagErrorBuf contains all error messages from pflag.
+	flagErrorBuf *bytes.Buffer
+	// flags is full set of flags.
+	flags *flag.FlagSet
+	// pflags contains persistent flags.
+	pflags *flag.FlagSet
+	// lflags contains local flags.
+	lflags *flag.FlagSet
+	// iflags contains inherited flags.
+	iflags *flag.FlagSet
+	// parentsPflags is all persistent flags of cmd's parents.
+	parentsPflags *flag.FlagSet
+	// globNormFunc is the global normalization function
+	// that we can use on every pflag set and children commands
+	globNormFunc func(f *flag.FlagSet, name string) flag.NormalizedName
+
+	// output is an output writer defined by user.
+	output io.Writer
+	// usageFunc is usage func defined by user.
+	usageFunc func(*Command) error
+	// usageTemplate is usage template defined by user.
+	usageTemplate string
+	// flagErrorFunc is func defined by user and it's called when the parsing of
+	// flags returns an error.
+	flagErrorFunc func(*Command, error) error
+	// helpTemplate is help template defined by user.
+	helpTemplate string
+	// helpFunc is help func defined by user.
+	helpFunc func(*Command, []string)
+	// helpCommand is command with usage 'help'. If it's not defined by user,
+	// cobra uses default help command.
+	helpCommand *Command
+	// versionTemplate is the version template defined by user.
+	versionTemplate string
+}
+
+// SetArgs sets arguments for the command. It is set to os.Args[1:] by default, if desired, can be overridden
+// particularly useful when testing.
+func (c *Command) SetArgs(a []string) {
+	c.args = a
+}
+
+// SetOutput sets the destination for usage and error messages.
+// If output is nil, os.Stderr is used.
+func (c *Command) SetOutput(output io.Writer) {
+	c.output = output
+}
+
+// SetUsageFunc sets usage function. Usage can be defined by application.
+func (c *Command) SetUsageFunc(f func(*Command) error) {
+	c.usageFunc = f
+}
+
+// SetUsageTemplate sets usage template. Can be defined by Application.
+func (c *Command) SetUsageTemplate(s string) {
+	c.usageTemplate = s
+}
+
+// SetFlagErrorFunc sets a function to generate an error when flag parsing
+// fails.
+func (c *Command) SetFlagErrorFunc(f func(*Command, error) error) {
+	c.flagErrorFunc = f
+}
+
+// SetHelpFunc sets help function. Can be defined by Application.
+func (c *Command) SetHelpFunc(f func(*Command, []string)) {
+	c.helpFunc = f
+}
+
+// SetHelpCommand sets help command.
+func (c *Command) SetHelpCommand(cmd *Command) {
+	c.helpCommand = cmd
+}
+
+// SetHelpTemplate sets help template to be used. Application can use it to set custom template.
+func (c *Command) SetHelpTemplate(s string) {
+	c.helpTemplate = s
+}
+
+// SetVersionTemplate sets version template to be used. Application can use it to set custom template.
+func (c *Command) SetVersionTemplate(s string) {
+	c.versionTemplate = s
+}
+
+// SetGlobalNormalizationFunc sets a normalization function to all flag sets and also to child commands.
+// The user should not have a cyclic dependency on commands.
+func (c *Command) SetGlobalNormalizationFunc(n func(f *flag.FlagSet, name string) flag.NormalizedName) {
+	c.Flags().SetNormalizeFunc(n)
+	c.PersistentFlags().SetNormalizeFunc(n)
+	c.globNormFunc = n
+
+	for _, command := range c.commands {
+		command.SetGlobalNormalizationFunc(n)
+	}
+}
+
+// OutOrStdout returns output to stdout.
+func (c *Command) OutOrStdout() io.Writer {
+	return c.getOut(os.Stdout)
+}
+
+// OutOrStderr returns output to stderr
+func (c *Command) OutOrStderr() io.Writer {
+	return c.getOut(os.Stderr)
+}
+
+func (c *Command) getOut(def io.Writer) io.Writer {
+	if c.output != nil {
+		return c.output
+	}
+	if c.HasParent() {
+		return c.parent.getOut(def)
+	}
+	return def
+}
+
+// UsageFunc returns either the function set by SetUsageFunc for this command
+// or a parent, or it returns a default usage function.
+func (c *Command) UsageFunc() (f func(*Command) error) {
+	if c.usageFunc != nil {
+		return c.usageFunc
+	}
+	if c.HasParent() {
+		return c.Parent().UsageFunc()
+	}
+	return func(c *Command) error {
+		c.mergePersistentFlags()
+		err := tmpl(c.OutOrStderr(), c.UsageTemplate(), c)
+		if err != nil {
+			c.Println(err)
+		}
+		return err
+	}
+}
+
+// Usage puts out the usage for the command.
+// Used when a user provides invalid input.
+// Can be defined by user by overriding UsageFunc.
+func (c *Command) Usage() error {
+	return c.UsageFunc()(c)
+}
+
+// HelpFunc returns either the function set by SetHelpFunc for this command
+// or a parent, or it returns a function with default help behavior.
+func (c *Command) HelpFunc() func(*Command, []string) {
+	if c.helpFunc != nil {
+		return c.helpFunc
+	}
+	if c.HasParent() {
+		return c.Parent().HelpFunc()
+	}
+	return func(c *Command, a []string) {
+		c.mergePersistentFlags()
+		err := tmpl(c.OutOrStdout(), c.HelpTemplate(), c)
+		if err != nil {
+			c.Println(err)
+		}
+	}
+}
+
+// Help puts out the help for the command.
+// Used when a user calls help [command].
+// Can be defined by user by overriding HelpFunc.
+func (c *Command) Help() error {
+	c.HelpFunc()(c, []string{})
+	return nil
+}
+
+// UsageString return usage string.
+func (c *Command) UsageString() string {
+	tmpOutput := c.output
+	bb := new(bytes.Buffer)
+	c.SetOutput(bb)
+	c.Usage()
+	c.output = tmpOutput
+	return bb.String()
+}
+
+// FlagErrorFunc returns either the function set by SetFlagErrorFunc for this
+// command or a parent, or it returns a function which returns the original
+// error.
+func (c *Command) FlagErrorFunc() (f func(*Command, error) error) {
+	if c.flagErrorFunc != nil {
+		return c.flagErrorFunc
+	}
+
+	if c.HasParent() {
+		return c.parent.FlagErrorFunc()
+	}
+	return func(c *Command, err error) error {
+		return err
+	}
+}
+
+var minUsagePadding = 25
+
+// UsagePadding return padding for the usage.
+func (c *Command) UsagePadding() int {
+	if c.parent == nil || minUsagePadding > c.parent.commandsMaxUseLen {
+		return minUsagePadding
+	}
+	return c.parent.commandsMaxUseLen
+}
+
+var minCommandPathPadding = 11
+
+// CommandPathPadding return padding for the command path.
+func (c *Command) CommandPathPadding() int {
+	if c.parent == nil || minCommandPathPadding > c.parent.commandsMaxCommandPathLen {
+		return minCommandPathPadding
+	}
+	return c.parent.commandsMaxCommandPathLen
+}
+
+var minNamePadding = 11
+
+// NamePadding returns padding for the name.
+func (c *Command) NamePadding() int {
+	if c.parent == nil || minNamePadding > c.parent.commandsMaxNameLen {
+		return minNamePadding
+	}
+	return c.parent.commandsMaxNameLen
+}
+
+// UsageTemplate returns usage template for the command.
+func (c *Command) UsageTemplate() string {
+	if c.usageTemplate != "" {
+		return c.usageTemplate
+	}
+
+	if c.HasParent() {
+		return c.parent.UsageTemplate()
+	}
+	return `Usage:{{if .Runnable}}
+  {{.UseLine}}{{end}}{{if .HasAvailableSubCommands}}
+  {{.CommandPath}} [command]{{end}}{{if gt (len .Aliases) 0}}
+
+Aliases:
+  {{.NameAndAliases}}{{end}}{{if .HasExample}}
+
+Examples:
+{{.Example}}{{end}}{{if .HasAvailableSubCommands}}
+
+Available Commands:{{range .Commands}}{{if (or .IsAvailableCommand (eq .Name "help"))}}
+  {{rpad .Name .NamePadding }} {{.Short}}{{end}}{{end}}{{end}}{{if .HasAvailableLocalFlags}}
+
+Flags:
+{{.LocalFlags.FlagUsages | trimTrailingWhitespaces}}{{end}}{{if .HasAvailableInheritedFlags}}
+
+Global Flags:
+{{.InheritedFlags.FlagUsages | trimTrailingWhitespaces}}{{end}}{{if .HasHelpSubCommands}}
+
+Additional help topics:{{range .Commands}}{{if .IsAdditionalHelpTopicCommand}}
+  {{rpad .CommandPath .CommandPathPadding}} {{.Short}}{{end}}{{end}}{{end}}{{if .HasAvailableSubCommands}}
+
+Use "{{.CommandPath}} [command] --help" for more information about a command.{{end}}
+`
+}
+
+// HelpTemplate return help template for the command.
+func (c *Command) HelpTemplate() string {
+	if c.helpTemplate != "" {
+		return c.helpTemplate
+	}
+
+	if c.HasParent() {
+		return c.parent.HelpTemplate()
+	}
+	return `{{with (or .Long .Short)}}{{. | trimTrailingWhitespaces}}
+
+{{end}}{{if or .Runnable .HasSubCommands}}{{.UsageString}}{{end}}`
+}
+
+// VersionTemplate return version template for the command.
+func (c *Command) VersionTemplate() string {
+	if c.versionTemplate != "" {
+		return c.versionTemplate
+	}
+
+	if c.HasParent() {
+		return c.parent.VersionTemplate()
+	}
+	return `{{with .Name}}{{printf "%s " .}}{{end}}{{printf "version %s" .Version}}
+`
+}
+
+func hasNoOptDefVal(name string, fs *flag.FlagSet) bool {
+	flag := fs.Lookup(name)
+	if flag == nil {
+		return false
+	}
+	return flag.NoOptDefVal != ""
+}
+
+func shortHasNoOptDefVal(name string, fs *flag.FlagSet) bool {
+	if len(name) == 0 {
+		return false
+	}
+
+	flag := fs.ShorthandLookup(name[:1])
+	if flag == nil {
+		return false
+	}
+	return flag.NoOptDefVal != ""
+}
+
+func stripFlags(args []string, c *Command) []string {
+	if len(args) == 0 {
+		return args
+	}
+	c.mergePersistentFlags()
+
+	commands := []string{}
+	flags := c.Flags()
+
+Loop:
+	for len(args) > 0 {
+		s := args[0]
+		args = args[1:]
+		switch {
+		case s == "--":
+			// "--" terminates the flags
+			break Loop
+		case strings.HasPrefix(s, "--") && !strings.Contains(s, "=") && !hasNoOptDefVal(s[2:], flags):
+			// If '--flag arg' then
+			// delete arg from args.
+			fallthrough // (do the same as below)
+		case strings.HasPrefix(s, "-") && !strings.Contains(s, "=") && len(s) == 2 && !shortHasNoOptDefVal(s[1:], flags):
+			// If '-f arg' then
+			// delete 'arg' from args or break the loop if len(args) <= 1.
+			if len(args) <= 1 {
+				break Loop
+			} else {
+				args = args[1:]
+				continue
+			}
+		case s != "" && !strings.HasPrefix(s, "-"):
+			commands = append(commands, s)
+		}
+	}
+
+	return commands
+}
+
+// argsMinusFirstX removes only the first x from args.  Otherwise, commands that look like
+// openshift admin policy add-role-to-user admin my-user, lose the admin argument (arg[4]).
+func argsMinusFirstX(args []string, x string) []string {
+	for i, y := range args {
+		if x == y {
+			ret := []string{}
+			ret = append(ret, args[:i]...)
+			ret = append(ret, args[i+1:]...)
+			return ret
+		}
+	}
+	return args
+}
+
+func isFlagArg(arg string) bool {
+	return ((len(arg) >= 3 && arg[1] == '-') ||
+		(len(arg) >= 2 && arg[0] == '-' && arg[1] != '-'))
+}
+
+// Find the target command given the args and command tree
+// Meant to be run on the highest node. Only searches down.
+func (c *Command) Find(args []string) (*Command, []string, error) {
+	var innerfind func(*Command, []string) (*Command, []string)
+
+	innerfind = func(c *Command, innerArgs []string) (*Command, []string) {
+		argsWOflags := stripFlags(innerArgs, c)
+		if len(argsWOflags) == 0 {
+			return c, innerArgs
+		}
+		nextSubCmd := argsWOflags[0]
+
+		cmd := c.findNext(nextSubCmd)
+		if cmd != nil {
+			return innerfind(cmd, argsMinusFirstX(innerArgs, nextSubCmd))
+		}
+		return c, innerArgs
+	}
+
+	commandFound, a := innerfind(c, args)
+	if commandFound.Args == nil {
+		return commandFound, a, legacyArgs(commandFound, stripFlags(a, commandFound))
+	}
+	return commandFound, a, nil
+}
+
+func (c *Command) findSuggestions(arg string) string {
+	if c.DisableSuggestions {
+		return ""
+	}
+	if c.SuggestionsMinimumDistance <= 0 {
+		c.SuggestionsMinimumDistance = 2
+	}
+	suggestionsString := ""
+	if suggestions := c.SuggestionsFor(arg); len(suggestions) > 0 {
+		suggestionsString += "\n\nDid you mean this?\n"
+		for _, s := range suggestions {
+			suggestionsString += fmt.Sprintf("\t%v\n", s)
+		}
+	}
+	return suggestionsString
+}
+
+func (c *Command) findNext(next string) *Command {
+	matches := make([]*Command, 0)
+	for _, cmd := range c.commands {
+		if cmd.Name() == next || cmd.HasAlias(next) {
+			cmd.commandCalledAs.name = next
+			return cmd
+		}
+		if EnablePrefixMatching && cmd.hasNameOrAliasPrefix(next) {
+			matches = append(matches, cmd)
+		}
+	}
+
+	if len(matches) == 1 {
+		return matches[0]
+	}
+
+	return nil
+}
+
+// Traverse the command tree to find the command, and parse args for
+// each parent.
+func (c *Command) Traverse(args []string) (*Command, []string, error) {
+	flags := []string{}
+	inFlag := false
+
+	for i, arg := range args {
+		switch {
+		// A long flag with a space separated value
+		case strings.HasPrefix(arg, "--") && !strings.Contains(arg, "="):
+			// TODO: this isn't quite right, we should really check ahead for 'true' or 'false'
+			inFlag = !hasNoOptDefVal(arg[2:], c.Flags())
+			flags = append(flags, arg)
+			continue
+		// A short flag with a space separated value
+		case strings.HasPrefix(arg, "-") && !strings.Contains(arg, "=") && len(arg) == 2 && !shortHasNoOptDefVal(arg[1:], c.Flags()):
+			inFlag = true
+			flags = append(flags, arg)
+			continue
+		// The value for a flag
+		case inFlag:
+			inFlag = false
+			flags = append(flags, arg)
+			continue
+		// A flag without a value, or with an `=` separated value
+		case isFlagArg(arg):
+			flags = append(flags, arg)
+			continue
+		}
+
+		cmd := c.findNext(arg)
+		if cmd == nil {
+			return c, args, nil
+		}
+
+		if err := c.ParseFlags(flags); err != nil {
+			return nil, args, err
+		}
+		return cmd.Traverse(args[i+1:])
+	}
+	return c, args, nil
+}
+
+// SuggestionsFor provides suggestions for the typedName.
+func (c *Command) SuggestionsFor(typedName string) []string {
+	suggestions := []string{}
+	for _, cmd := range c.commands {
+		if cmd.IsAvailableCommand() {
+			levenshteinDistance := ld(typedName, cmd.Name(), true)
+			suggestByLevenshtein := levenshteinDistance <= c.SuggestionsMinimumDistance
+			suggestByPrefix := strings.HasPrefix(strings.ToLower(cmd.Name()), strings.ToLower(typedName))
+			if suggestByLevenshtein || suggestByPrefix {
+				suggestions = append(suggestions, cmd.Name())
+			}
+			for _, explicitSuggestion := range cmd.SuggestFor {
+				if strings.EqualFold(typedName, explicitSuggestion) {
+					suggestions = append(suggestions, cmd.Name())
+				}
+			}
+		}
+	}
+	return suggestions
+}
+
+// VisitParents visits all parents of the command and invokes fn on each parent.
+func (c *Command) VisitParents(fn func(*Command)) {
+	if c.HasParent() {
+		fn(c.Parent())
+		c.Parent().VisitParents(fn)
+	}
+}
+
+// Root finds root command.
+func (c *Command) Root() *Command {
+	if c.HasParent() {
+		return c.Parent().Root()
+	}
+	return c
+}
+
+// ArgsLenAtDash will return the length of c.Flags().Args at the moment
+// when a -- was found during args parsing.
+func (c *Command) ArgsLenAtDash() int {
+	return c.Flags().ArgsLenAtDash()
+}
+
+func (c *Command) execute(a []string) (err error) {
+	if c == nil {
+		return fmt.Errorf("Called Execute() on a nil Command")
+	}
+
+	if len(c.Deprecated) > 0 {
+		c.Printf("Command %q is deprecated, %s\n", c.Name(), c.Deprecated)
+	}
+
+	// initialize help and version flag at the last point possible to allow for user
+	// overriding
+	c.InitDefaultHelpFlag()
+	c.InitDefaultVersionFlag()
+
+	err = c.ParseFlags(a)
+	if err != nil {
+		return c.FlagErrorFunc()(c, err)
+	}
+
+	// If help is called, regardless of other flags, return we want help.
+	// Also say we need help if the command isn't runnable.
+	helpVal, err := c.Flags().GetBool("help")
+	if err != nil {
+		// should be impossible to get here as we always declare a help
+		// flag in InitDefaultHelpFlag()
+		c.Println("\"help\" flag declared as non-bool. Please correct your code")
+		return err
+	}
+
+	if helpVal {
+		return flag.ErrHelp
+	}
+
+	// for back-compat, only add version flag behavior if version is defined
+	if c.Version != "" {
+		versionVal, err := c.Flags().GetBool("version")
+		if err != nil {
+			c.Println("\"version\" flag declared as non-bool. Please correct your code")
+			return err
+		}
+		if versionVal {
+			err := tmpl(c.OutOrStdout(), c.VersionTemplate(), c)
+			if err != nil {
+				c.Println(err)
+			}
+			return err
+		}
+	}
+
+	if !c.Runnable() {
+		return flag.ErrHelp
+	}
+
+	c.preRun()
+
+	argWoFlags := c.Flags().Args()
+	if c.DisableFlagParsing {
+		argWoFlags = a
+	}
+
+	if err := c.ValidateArgs(argWoFlags); err != nil {
+		return err
+	}
+
+	for p := c; p != nil; p = p.Parent() {
+		if p.PersistentPreRunE != nil {
+			if err := p.PersistentPreRunE(c, argWoFlags); err != nil {
+				return err
+			}
+			break
+		} else if p.PersistentPreRun != nil {
+			p.PersistentPreRun(c, argWoFlags)
+			break
+		}
+	}
+	if c.PreRunE != nil {
+		if err := c.PreRunE(c, argWoFlags); err != nil {
+			return err
+		}
+	} else if c.PreRun != nil {
+		c.PreRun(c, argWoFlags)
+	}
+
+	if err := c.validateRequiredFlags(); err != nil {
+		return err
+	}
+	if c.RunE != nil {
+		if err := c.RunE(c, argWoFlags); err != nil {
+			return err
+		}
+	} else {
+		c.Run(c, argWoFlags)
+	}
+	if c.PostRunE != nil {
+		if err := c.PostRunE(c, argWoFlags); err != nil {
+			return err
+		}
+	} else if c.PostRun != nil {
+		c.PostRun(c, argWoFlags)
+	}
+	for p := c; p != nil; p = p.Parent() {
+		if p.PersistentPostRunE != nil {
+			if err := p.PersistentPostRunE(c, argWoFlags); err != nil {
+				return err
+			}
+			break
+		} else if p.PersistentPostRun != nil {
+			p.PersistentPostRun(c, argWoFlags)
+			break
+		}
+	}
+
+	return nil
+}
+
+func (c *Command) preRun() {
+	for _, x := range initializers {
+		x()
+	}
+}
+
+// Execute uses the args (os.Args[1:] by default)
+// and run through the command tree finding appropriate matches
+// for commands and then corresponding flags.
+func (c *Command) Execute() error {
+	_, err := c.ExecuteC()
+	return err
+}
+
+// ExecuteC executes the command.
+func (c *Command) ExecuteC() (cmd *Command, err error) {
+	// Regardless of what command execute is called on, run on Root only
+	if c.HasParent() {
+		return c.Root().ExecuteC()
+	}
+
+	// windows hook
+	if preExecHookFn != nil {
+		preExecHookFn(c)
+	}
+
+	// initialize help as the last point possible to allow for user
+	// overriding
+	c.InitDefaultHelpCmd()
+
+	var args []string
+
+	// Workaround FAIL with "go test -v" or "cobra.test -test.v", see #155
+	if c.args == nil && filepath.Base(os.Args[0]) != "cobra.test" {
+		args = os.Args[1:]
+	} else {
+		args = c.args
+	}
+
+	var flags []string
+	if c.TraverseChildren {
+		cmd, flags, err = c.Traverse(args)
+	} else {
+		cmd, flags, err = c.Find(args)
+	}
+	if err != nil {
+		// If found parse to a subcommand and then failed, talk about the subcommand
+		if cmd != nil {
+			c = cmd
+		}
+		if !c.SilenceErrors {
+			c.Println("Error:", err.Error())
+			c.Printf("Run '%v --help' for usage.\n", c.CommandPath())
+		}
+		return c, err
+	}
+
+	cmd.commandCalledAs.called = true
+	if cmd.commandCalledAs.name == "" {
+		cmd.commandCalledAs.name = cmd.Name()
+	}
+
+	err = cmd.execute(flags)
+	if err != nil {
+		// Always show help if requested, even if SilenceErrors is in
+		// effect
+		if err == flag.ErrHelp {
+			cmd.HelpFunc()(cmd, args)
+			return cmd, nil
+		}
+
+		// If root command has SilentErrors flagged,
+		// all subcommands should respect it
+		if !cmd.SilenceErrors && !c.SilenceErrors {
+			c.Println("Error:", err.Error())
+		}
+
+		// If root command has SilentUsage flagged,
+		// all subcommands should respect it
+		if !cmd.SilenceUsage && !c.SilenceUsage {
+			c.Println(cmd.UsageString())
+		}
+	}
+	return cmd, err
+}
+
+func (c *Command) ValidateArgs(args []string) error {
+	if c.Args == nil {
+		return nil
+	}
+	return c.Args(c, args)
+}
+
+func (c *Command) validateRequiredFlags() error {
+	flags := c.Flags()
+	missingFlagNames := []string{}
+	flags.VisitAll(func(pflag *flag.Flag) {
+		requiredAnnotation, found := pflag.Annotations[BashCompOneRequiredFlag]
+		if !found {
+			return
+		}
+		if (requiredAnnotation[0] == "true") && !pflag.Changed {
+			missingFlagNames = append(missingFlagNames, pflag.Name)
+		}
+	})
+
+	if len(missingFlagNames) > 0 {
+		return fmt.Errorf(`required flag(s) "%s" not set`, strings.Join(missingFlagNames, `", "`))
+	}
+	return nil
+}
+
+// InitDefaultHelpFlag adds default help flag to c.
+// It is called automatically by executing the c or by calling help and usage.
+// If c already has help flag, it will do nothing.
+func (c *Command) InitDefaultHelpFlag() {
+	c.mergePersistentFlags()
+	if c.Flags().Lookup("help") == nil {
+		usage := "help for "
+		if c.Name() == "" {
+			usage += "this command"
+		} else {
+			usage += c.Name()
+		}
+		c.Flags().BoolP("help", "h", false, usage)
+	}
+}
+
+// InitDefaultVersionFlag adds default version flag to c.
+// It is called automatically by executing the c.
+// If c already has a version flag, it will do nothing.
+// If c.Version is empty, it will do nothing.
+func (c *Command) InitDefaultVersionFlag() {
+	if c.Version == "" {
+		return
+	}
+
+	c.mergePersistentFlags()
+	if c.Flags().Lookup("version") == nil {
+		usage := "version for "
+		if c.Name() == "" {
+			usage += "this command"
+		} else {
+			usage += c.Name()
+		}
+		c.Flags().Bool("version", false, usage)
+	}
+}
+
+// InitDefaultHelpCmd adds default help command to c.
+// It is called automatically by executing the c or by calling help and usage.
+// If c already has help command or c has no subcommands, it will do nothing.
+func (c *Command) InitDefaultHelpCmd() {
+	if !c.HasSubCommands() {
+		return
+	}
+
+	if c.helpCommand == nil {
+		c.helpCommand = &Command{
+			Use:   "help [command]",
+			Short: "Help about any command",
+			Long: `Help provides help for any command in the application.
+Simply type ` + c.Name() + ` help [path to command] for full details.`,
+
+			Run: func(c *Command, args []string) {
+				cmd, _, e := c.Root().Find(args)
+				if cmd == nil || e != nil {
+					c.Printf("Unknown help topic %#q\n", args)
+					c.Root().Usage()
+				} else {
+					cmd.InitDefaultHelpFlag() // make possible 'help' flag to be shown
+					cmd.Help()
+				}
+			},
+		}
+	}
+	c.RemoveCommand(c.helpCommand)
+	c.AddCommand(c.helpCommand)
+}
+
+// ResetCommands delete parent, subcommand and help command from c.
+func (c *Command) ResetCommands() {
+	c.parent = nil
+	c.commands = nil
+	c.helpCommand = nil
+	c.parentsPflags = nil
+}
+
+// Sorts commands by their names.
+type commandSorterByName []*Command
+
+func (c commandSorterByName) Len() int           { return len(c) }
+func (c commandSorterByName) Swap(i, j int)      { c[i], c[j] = c[j], c[i] }
+func (c commandSorterByName) Less(i, j int) bool { return c[i].Name() < c[j].Name() }
+
+// Commands returns a sorted slice of child commands.
+func (c *Command) Commands() []*Command {
+	// do not sort commands if it already sorted or sorting was disabled
+	if EnableCommandSorting && !c.commandsAreSorted {
+		sort.Sort(commandSorterByName(c.commands))
+		c.commandsAreSorted = true
+	}
+	return c.commands
+}
+
+// AddCommand adds one or more commands to this parent command.
+func (c *Command) AddCommand(cmds ...*Command) {
+	for i, x := range cmds {
+		if cmds[i] == c {
+			panic("Command can't be a child of itself")
+		}
+		cmds[i].parent = c
+		// update max lengths
+		usageLen := len(x.Use)
+		if usageLen > c.commandsMaxUseLen {
+			c.commandsMaxUseLen = usageLen
+		}
+		commandPathLen := len(x.CommandPath())
+		if commandPathLen > c.commandsMaxCommandPathLen {
+			c.commandsMaxCommandPathLen = commandPathLen
+		}
+		nameLen := len(x.Name())
+		if nameLen > c.commandsMaxNameLen {
+			c.commandsMaxNameLen = nameLen
+		}
+		// If global normalization function exists, update all children
+		if c.globNormFunc != nil {
+			x.SetGlobalNormalizationFunc(c.globNormFunc)
+		}
+		c.commands = append(c.commands, x)
+		c.commandsAreSorted = false
+	}
+}
+
+// RemoveCommand removes one or more commands from a parent command.
+func (c *Command) RemoveCommand(cmds ...*Command) {
+	commands := []*Command{}
+main:
+	for _, command := range c.commands {
+		for _, cmd := range cmds {
+			if command == cmd {
+				command.parent = nil
+				continue main
+			}
+		}
+		commands = append(commands, command)
+	}
+	c.commands = commands
+	// recompute all lengths
+	c.commandsMaxUseLen = 0
+	c.commandsMaxCommandPathLen = 0
+	c.commandsMaxNameLen = 0
+	for _, command := range c.commands {
+		usageLen := len(command.Use)
+		if usageLen > c.commandsMaxUseLen {
+			c.commandsMaxUseLen = usageLen
+		}
+		commandPathLen := len(command.CommandPath())
+		if commandPathLen > c.commandsMaxCommandPathLen {
+			c.commandsMaxCommandPathLen = commandPathLen
+		}
+		nameLen := len(command.Name())
+		if nameLen > c.commandsMaxNameLen {
+			c.commandsMaxNameLen = nameLen
+		}
+	}
+}
+
+// Print is a convenience method to Print to the defined output, fallback to Stderr if not set.
+func (c *Command) Print(i ...interface{}) {
+	fmt.Fprint(c.OutOrStderr(), i...)
+}
+
+// Println is a convenience method to Println to the defined output, fallback to Stderr if not set.
+func (c *Command) Println(i ...interface{}) {
+	c.Print(fmt.Sprintln(i...))
+}
+
+// Printf is a convenience method to Printf to the defined output, fallback to Stderr if not set.
+func (c *Command) Printf(format string, i ...interface{}) {
+	c.Print(fmt.Sprintf(format, i...))
+}
+
+// CommandPath returns the full path to this command.
+func (c *Command) CommandPath() string {
+	if c.HasParent() {
+		return c.Parent().CommandPath() + " " + c.Name()
+	}
+	return c.Name()
+}
+
+// UseLine puts out the full usage for a given command (including parents).
+func (c *Command) UseLine() string {
+	var useline string
+	if c.HasParent() {
+		useline = c.parent.CommandPath() + " " + c.Use
+	} else {
+		useline = c.Use
+	}
+	if c.DisableFlagsInUseLine {
+		return useline
+	}
+	if c.HasAvailableFlags() && !strings.Contains(useline, "[flags]") {
+		useline += " [flags]"
+	}
+	return useline
+}
+
+// DebugFlags used to determine which flags have been assigned to which commands
+// and which persist.
+func (c *Command) DebugFlags() {
+	c.Println("DebugFlags called on", c.Name())
+	var debugflags func(*Command)
+
+	debugflags = func(x *Command) {
+		if x.HasFlags() || x.HasPersistentFlags() {
+			c.Println(x.Name())
+		}
+		if x.HasFlags() {
+			x.flags.VisitAll(func(f *flag.Flag) {
+				if x.HasPersistentFlags() && x.persistentFlag(f.Name) != nil {
+					c.Println("  -"+f.Shorthand+",", "--"+f.Name, "["+f.DefValue+"]", "", f.Value, "  [LP]")
+				} else {
+					c.Println("  -"+f.Shorthand+",", "--"+f.Name, "["+f.DefValue+"]", "", f.Value, "  [L]")
+				}
+			})
+		}
+		if x.HasPersistentFlags() {
+			x.pflags.VisitAll(func(f *flag.Flag) {
+				if x.HasFlags() {
+					if x.flags.Lookup(f.Name) == nil {
+						c.Println("  -"+f.Shorthand+",", "--"+f.Name, "["+f.DefValue+"]", "", f.Value, "  [P]")
+					}
+				} else {
+					c.Println("  -"+f.Shorthand+",", "--"+f.Name, "["+f.DefValue+"]", "", f.Value, "  [P]")
+				}
+			})
+		}
+		c.Println(x.flagErrorBuf)
+		if x.HasSubCommands() {
+			for _, y := range x.commands {
+				debugflags(y)
+			}
+		}
+	}
+
+	debugflags(c)
+}
+
+// Name returns the command's name: the first word in the use line.
+func (c *Command) Name() string {
+	name := c.Use
+	i := strings.Index(name, " ")
+	if i >= 0 {
+		name = name[:i]
+	}
+	return name
+}
+
+// HasAlias determines if a given string is an alias of the command.
+func (c *Command) HasAlias(s string) bool {
+	for _, a := range c.Aliases {
+		if a == s {
+			return true
+		}
+	}
+	return false
+}
+
+// CalledAs returns the command name or alias that was used to invoke
+// this command or an empty string if the command has not been called.
+func (c *Command) CalledAs() string {
+	if c.commandCalledAs.called {
+		return c.commandCalledAs.name
+	}
+	return ""
+}
+
+// hasNameOrAliasPrefix returns true if the Name or any of aliases start
+// with prefix
+func (c *Command) hasNameOrAliasPrefix(prefix string) bool {
+	if strings.HasPrefix(c.Name(), prefix) {
+		c.commandCalledAs.name = c.Name()
+		return true
+	}
+	for _, alias := range c.Aliases {
+		if strings.HasPrefix(alias, prefix) {
+			c.commandCalledAs.name = alias
+			return true
+		}
+	}
+	return false
+}
+
+// NameAndAliases returns a list of the command name and all aliases
+func (c *Command) NameAndAliases() string {
+	return strings.Join(append([]string{c.Name()}, c.Aliases...), ", ")
+}
+
+// HasExample determines if the command has example.
+func (c *Command) HasExample() bool {
+	return len(c.Example) > 0
+}
+
+// Runnable determines if the command is itself runnable.
+func (c *Command) Runnable() bool {
+	return c.Run != nil || c.RunE != nil
+}
+
+// HasSubCommands determines if the command has children commands.
+func (c *Command) HasSubCommands() bool {
+	return len(c.commands) > 0
+}
+
+// IsAvailableCommand determines if a command is available as a non-help command
+// (this includes all non deprecated/hidden commands).
+func (c *Command) IsAvailableCommand() bool {
+	if len(c.Deprecated) != 0 || c.Hidden {
+		return false
+	}
+
+	if c.HasParent() && c.Parent().helpCommand == c {
+		return false
+	}
+
+	if c.Runnable() || c.HasAvailableSubCommands() {
+		return true
+	}
+
+	return false
+}
+
+// IsAdditionalHelpTopicCommand determines if a command is an additional
+// help topic command; additional help topic command is determined by the
+// fact that it is NOT runnable/hidden/deprecated, and has no sub commands that
+// are runnable/hidden/deprecated.
+// Concrete example: https://github.com/spf13/cobra/issues/393#issuecomment-282741924.
+func (c *Command) IsAdditionalHelpTopicCommand() bool {
+	// if a command is runnable, deprecated, or hidden it is not a 'help' command
+	if c.Runnable() || len(c.Deprecated) != 0 || c.Hidden {
+		return false
+	}
+
+	// if any non-help sub commands are found, the command is not a 'help' command
+	for _, sub := range c.commands {
+		if !sub.IsAdditionalHelpTopicCommand() {
+			return false
+		}
+	}
+
+	// the command either has no sub commands, or no non-help sub commands
+	return true
+}
+
+// HasHelpSubCommands determines if a command has any available 'help' sub commands
+// that need to be shown in the usage/help default template under 'additional help
+// topics'.
+func (c *Command) HasHelpSubCommands() bool {
+	// return true on the first found available 'help' sub command
+	for _, sub := range c.commands {
+		if sub.IsAdditionalHelpTopicCommand() {
+			return true
+		}
+	}
+
+	// the command either has no sub commands, or no available 'help' sub commands
+	return false
+}
+
+// HasAvailableSubCommands determines if a command has available sub commands that
+// need to be shown in the usage/help default template under 'available commands'.
+func (c *Command) HasAvailableSubCommands() bool {
+	// return true on the first found available (non deprecated/help/hidden)
+	// sub command
+	for _, sub := range c.commands {
+		if sub.IsAvailableCommand() {
+			return true
+		}
+	}
+
+	// the command either has no sub commands, or no available (non deprecated/help/hidden)
+	// sub commands
+	return false
+}
+
+// HasParent determines if the command is a child command.
+func (c *Command) HasParent() bool {
+	return c.parent != nil
+}
+
+// GlobalNormalizationFunc returns the global normalization function or nil if it doesn't exist.
+func (c *Command) GlobalNormalizationFunc() func(f *flag.FlagSet, name string) flag.NormalizedName {
+	return c.globNormFunc
+}
+
+// Flags returns the complete FlagSet that applies
+// to this command (local and persistent declared here and by all parents).
+func (c *Command) Flags() *flag.FlagSet {
+	if c.flags == nil {
+		c.flags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+		if c.flagErrorBuf == nil {
+			c.flagErrorBuf = new(bytes.Buffer)
+		}
+		c.flags.SetOutput(c.flagErrorBuf)
+	}
+
+	return c.flags
+}
+
+// LocalNonPersistentFlags are flags specific to this command which will NOT persist to subcommands.
+func (c *Command) LocalNonPersistentFlags() *flag.FlagSet {
+	persistentFlags := c.PersistentFlags()
+
+	out := flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+	c.LocalFlags().VisitAll(func(f *flag.Flag) {
+		if persistentFlags.Lookup(f.Name) == nil {
+			out.AddFlag(f)
+		}
+	})
+	return out
+}
+
+// LocalFlags returns the local FlagSet specifically set in the current command.
+func (c *Command) LocalFlags() *flag.FlagSet {
+	c.mergePersistentFlags()
+
+	if c.lflags == nil {
+		c.lflags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+		if c.flagErrorBuf == nil {
+			c.flagErrorBuf = new(bytes.Buffer)
+		}
+		c.lflags.SetOutput(c.flagErrorBuf)
+	}
+	c.lflags.SortFlags = c.Flags().SortFlags
+	if c.globNormFunc != nil {
+		c.lflags.SetNormalizeFunc(c.globNormFunc)
+	}
+
+	addToLocal := func(f *flag.Flag) {
+		if c.lflags.Lookup(f.Name) == nil && c.parentsPflags.Lookup(f.Name) == nil {
+			c.lflags.AddFlag(f)
+		}
+	}
+	c.Flags().VisitAll(addToLocal)
+	c.PersistentFlags().VisitAll(addToLocal)
+	return c.lflags
+}
+
+// InheritedFlags returns all flags which were inherited from parents commands.
+func (c *Command) InheritedFlags() *flag.FlagSet {
+	c.mergePersistentFlags()
+
+	if c.iflags == nil {
+		c.iflags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+		if c.flagErrorBuf == nil {
+			c.flagErrorBuf = new(bytes.Buffer)
+		}
+		c.iflags.SetOutput(c.flagErrorBuf)
+	}
+
+	local := c.LocalFlags()
+	if c.globNormFunc != nil {
+		c.iflags.SetNormalizeFunc(c.globNormFunc)
+	}
+
+	c.parentsPflags.VisitAll(func(f *flag.Flag) {
+		if c.iflags.Lookup(f.Name) == nil && local.Lookup(f.Name) == nil {
+			c.iflags.AddFlag(f)
+		}
+	})
+	return c.iflags
+}
+
+// NonInheritedFlags returns all flags which were not inherited from parent commands.
+func (c *Command) NonInheritedFlags() *flag.FlagSet {
+	return c.LocalFlags()
+}
+
+// PersistentFlags returns the persistent FlagSet specifically set in the current command.
+func (c *Command) PersistentFlags() *flag.FlagSet {
+	if c.pflags == nil {
+		c.pflags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+		if c.flagErrorBuf == nil {
+			c.flagErrorBuf = new(bytes.Buffer)
+		}
+		c.pflags.SetOutput(c.flagErrorBuf)
+	}
+	return c.pflags
+}
+
+// ResetFlags deletes all flags from command.
+func (c *Command) ResetFlags() {
+	c.flagErrorBuf = new(bytes.Buffer)
+	c.flagErrorBuf.Reset()
+	c.flags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+	c.flags.SetOutput(c.flagErrorBuf)
+	c.pflags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+	c.pflags.SetOutput(c.flagErrorBuf)
+
+	c.lflags = nil
+	c.iflags = nil
+	c.parentsPflags = nil
+}
+
+// HasFlags checks if the command contains any flags (local plus persistent from the entire structure).
+func (c *Command) HasFlags() bool {
+	return c.Flags().HasFlags()
+}
+
+// HasPersistentFlags checks if the command contains persistent flags.
+func (c *Command) HasPersistentFlags() bool {
+	return c.PersistentFlags().HasFlags()
+}
+
+// HasLocalFlags checks if the command has flags specifically declared locally.
+func (c *Command) HasLocalFlags() bool {
+	return c.LocalFlags().HasFlags()
+}
+
+// HasInheritedFlags checks if the command has flags inherited from its parent command.
+func (c *Command) HasInheritedFlags() bool {
+	return c.InheritedFlags().HasFlags()
+}
+
+// HasAvailableFlags checks if the command contains any flags (local plus persistent from the entire
+// structure) which are not hidden or deprecated.
+func (c *Command) HasAvailableFlags() bool {
+	return c.Flags().HasAvailableFlags()
+}
+
+// HasAvailablePersistentFlags checks if the command contains persistent flags which are not hidden or deprecated.
+func (c *Command) HasAvailablePersistentFlags() bool {
+	return c.PersistentFlags().HasAvailableFlags()
+}
+
+// HasAvailableLocalFlags checks if the command has flags specifically declared locally which are not hidden
+// or deprecated.
+func (c *Command) HasAvailableLocalFlags() bool {
+	return c.LocalFlags().HasAvailableFlags()
+}
+
+// HasAvailableInheritedFlags checks if the command has flags inherited from its parent command which are
+// not hidden or deprecated.
+func (c *Command) HasAvailableInheritedFlags() bool {
+	return c.InheritedFlags().HasAvailableFlags()
+}
+
+// Flag climbs up the command tree looking for matching flag.
+func (c *Command) Flag(name string) (flag *flag.Flag) {
+	flag = c.Flags().Lookup(name)
+
+	if flag == nil {
+		flag = c.persistentFlag(name)
+	}
+
+	return
+}
+
+// Recursively find matching persistent flag.
+func (c *Command) persistentFlag(name string) (flag *flag.Flag) {
+	if c.HasPersistentFlags() {
+		flag = c.PersistentFlags().Lookup(name)
+	}
+
+	if flag == nil {
+		c.updateParentsPflags()
+		flag = c.parentsPflags.Lookup(name)
+	}
+	return
+}
+
+// ParseFlags parses persistent flag tree and local flags.
+func (c *Command) ParseFlags(args []string) error {
+	if c.DisableFlagParsing {
+		return nil
+	}
+
+	if c.flagErrorBuf == nil {
+		c.flagErrorBuf = new(bytes.Buffer)
+	}
+	beforeErrorBufLen := c.flagErrorBuf.Len()
+	c.mergePersistentFlags()
+
+	//do it here after merging all flags and just before parse
+	c.Flags().ParseErrorsWhitelist = flag.ParseErrorsWhitelist(c.FParseErrWhitelist)
+
+	err := c.Flags().Parse(args)
+	// Print warnings if they occurred (e.g. deprecated flag messages).
+	if c.flagErrorBuf.Len()-beforeErrorBufLen > 0 && err == nil {
+		c.Print(c.flagErrorBuf.String())
+	}
+
+	return err
+}
+
+// Parent returns a commands parent command.
+func (c *Command) Parent() *Command {
+	return c.parent
+}
+
+// mergePersistentFlags merges c.PersistentFlags() to c.Flags()
+// and adds missing persistent flags of all parents.
+func (c *Command) mergePersistentFlags() {
+	c.updateParentsPflags()
+	c.Flags().AddFlagSet(c.PersistentFlags())
+	c.Flags().AddFlagSet(c.parentsPflags)
+}
+
+// updateParentsPflags updates c.parentsPflags by adding
+// new persistent flags of all parents.
+// If c.parentsPflags == nil, it makes new.
+func (c *Command) updateParentsPflags() {
+	if c.parentsPflags == nil {
+		c.parentsPflags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+		c.parentsPflags.SetOutput(c.flagErrorBuf)
+		c.parentsPflags.SortFlags = false
+	}
+
+	if c.globNormFunc != nil {
+		c.parentsPflags.SetNormalizeFunc(c.globNormFunc)
+	}
+
+	c.Root().PersistentFlags().AddFlagSet(flag.CommandLine)
+
+	c.VisitParents(func(parent *Command) {
+		c.parentsPflags.AddFlagSet(parent.PersistentFlags())
+	})
+}