add help/version command

Makefile

@@ -7,6 +7,9 @@ BINARY := bin/$(BIN_NAME)
 GOLANGCI_LINT_VERSION := v1.52.2
 export GO111MODULE=on
 
+CMD_PACKAGE_DIR := github.com/konoui/lipo/cmd
+LDFLAGS := -X '$(CMD_PACKAGE_DIR).Version=$(VERSION)' -X '$(CMD_PACKAGE_DIR).Revision=$(REVISION)'
+
 ## Build binaries on your environment
 build:
 	CGO_ENABLED=0 go build -ldflags "$(LDFLAGS)" -o $(BINARY) $(SRC_DIR)

README.md

@@ -52,3 +52,9 @@ hello-world (for architecture arm64): Mach-O 64-bit executable arm64
 ### Supported Options
 
 `-archs`, `-create`, `-extract`, `-extract_family`, `-output`, `-remove`, `-replace`, `-segalign`, `-thin`, `-verify_arch`, `-arch`, `-info`, `-detailed_info`, `-hideARM64`, `-fat64`
+
+Please run the `-help` command for more details.
+
+```
+$ lipo -help
+```

cmd/execute.go

@@ -14,8 +14,15 @@ func fatal(w io.Writer, msg string) (exitCode int) {
 	return 1
 }
 
+var (
+	Version  = "*"
+	Revision = "*"
+)
+
 func Execute(stdout, stderr io.Writer, args []string) (exitCode int) {
 	fset := sflag.NewFlagSet("lipo")
+	helpGroup := fset.NewGroup("help")
+	versionGroup := fset.NewGroup("version")
 	createGroup := fset.NewGroup("create").AddDescription(createDescription)
 	thinGroup := fset.NewGroup("thin").AddDescription(thinDescription)
 	extractGroup := fset.NewGroup("extract").AddDescription(extractDescription)
@@ -26,12 +33,17 @@ func Execute(stdout, stderr io.Writer, args []string) (exitCode int) {
 	verifyArchGroup := fset.NewGroup("verify_arch").AddDescription(verifyArchDescription)
 	infoGroup := fset.NewGroup("info").AddDescription(infoDescription)
 	detailedInfoGroup := fset.NewGroup("detailed_info").AddDescription(detailedInfoDescription)
-	groups := []*sflag.Group{createGroup, thinGroup, extractGroup,
+	groups := []*sflag.Group{
+		helpGroup, versionGroup,
+		createGroup, thinGroup, extractGroup,
 		extractFamilyGroup, removeGroup, replaceGroup,
 		archsGroup, verifyArchGroup, infoGroup,
 		detailedInfoGroup,
 	}
 	fset.Usage = sflag.UsageFunc(groups...)
+	// original lipo does not have help/version command.
+	help := fset.Bool("help", "-help")
+	version := fset.Bool("version", "-version")
 	out := fset.String("output", "-output <output_file>", sflag.WithShortName("o"))
 	segAligns := fset.FixedStringFlags("segalign", "-segalign <arch_type> <alignment>", sflag.WithShortName("s"))
 	arch := fset.FixedStringFlags("arch", "-arch <arch_type> <input_file>", sflag.WithShortName("a"))
@@ -48,6 +60,8 @@ func Execute(stdout, stderr io.Writer, args []string) (exitCode int) {
 	hideArm64 := fset.Bool("hideARM64", "-hideARM64")
 	fat64 := fset.Bool("fat64", "-fat64")
 
+	helpGroup.AddRequired(help)
+	versionGroup.AddRequired(version)
 	createGroup.
 		AddRequired(create).
 		AddRequired(out).
@@ -188,8 +202,14 @@ func Execute(stdout, stderr io.Writer, args []string) (exitCode int) {
 			return 1
 		}
 		return
+	case "version":
+		fmt.Fprintf(stdout, "%s/%s\n", Version, Revision)
+		return 0
+	case "help":
+		fmt.Fprint(stdout, fset.Usage())
+		return 0
 	default:
-		fset.Usage()
+		fmt.Fprint(stderr, fset.Usage())
 		return 1
 	}
 }