feat: add ability to override usage text of default help command

godoc-current.txt

@@ -57,6 +57,10 @@ var AnyArguments = []Argument{
 }
     AnyArguments to differentiate between no arguments(nil) vs aleast one
 
+var ArgsUsageCommandHelp = "[command]"
+    ArgsUsageCommandHelp is a short description of the arguments of the help
+    command
+
 var CommandHelpTemplate = `NAME:
    {{template "helpNameTemplate" .}}
 
@@ -172,6 +176,10 @@ OPTIONS:{{template "visibleFlagTemplate" .}}{{end}}
     cli.go uses text/template to render templates. You can render custom help
     text by setting this variable.
 
+var UsageCommandHelp = "Shows a list of commands or help for one command"
+    UsageCommandHelp is the text to override the USAGE section of the help
+    command
+
 var VersionPrinter = DefaultPrintVersion
     VersionPrinter prints the version for the root Command.
 

help.go

@@ -56,12 +56,18 @@ var ShowCommandHelp = DefaultShowCommandHelp
 // ShowSubcommandHelp prints help for the given subcommand
 var ShowSubcommandHelp = DefaultShowSubcommandHelp
 
+// UsageCommandHelp is the text to override the USAGE section of the help command
+var UsageCommandHelp = "Shows a list of commands or help for one command"
+
+// ArgsUsageCommandHelp is a short description of the arguments of the help command
+var ArgsUsageCommandHelp = "[command]"
+
 func buildHelpCommand(withAction bool) *Command {
 	cmd := &Command{
 		Name:      helpName,
 		Aliases:   []string{helpAlias},
-		Usage:     "Shows a list of commands or help for one command",
-		ArgsUsage: "[command]",
+		Usage:     UsageCommandHelp,
+		ArgsUsage: ArgsUsageCommandHelp,
 		HideHelp:  true,
 	}
 

help_test.go

@@ -2009,3 +2009,26 @@ func TestPrintHelpCustomTemplateError(t *testing.T) {
 		*tmpl = oldtmpl
 	}
 }
+
+func TestCustomUsageCommandHelp(t *testing.T) {
+	old := UsageCommandHelp
+	defer func() { UsageCommandHelp = old }()
+
+	UsageCommandHelp = "Custom usage help command"
+
+	out := &bytes.Buffer{}
+	cmd := &Command{
+		Name: "app",
+		Commands: []*Command{
+			{
+				Name:     "cmd",
+				Commands: []*Command{{Name: "subcmd"}},
+			},
+		},
+		Writer:    out,
+		ErrWriter: out,
+	}
+
+	_ = cmd.Run(buildTestContext(t), []string{"app", "help"})
+	assert.Contains(t, out.String(), UsageCommandHelp)
+}

testdata/godoc-v3.x.txt

@@ -57,6 +57,10 @@ var AnyArguments = []Argument{
 }
     AnyArguments to differentiate between no arguments(nil) vs aleast one
 
+var ArgsUsageCommandHelp = "[command]"
+    ArgsUsageCommandHelp is a short description of the arguments of the help
+    command
+
 var CommandHelpTemplate = `NAME:
    {{template "helpNameTemplate" .}}
 
@@ -172,6 +176,10 @@ OPTIONS:{{template "visibleFlagTemplate" .}}{{end}}
     cli.go uses text/template to render templates. You can render custom help
     text by setting this variable.
 
+var UsageCommandHelp = "Shows a list of commands or help for one command"
+    UsageCommandHelp is the text to override the USAGE section of the help
+    command
+
 var VersionPrinter = DefaultPrintVersion
     VersionPrinter prints the version for the root Command.