help

main.go

@@ -13,12 +13,23 @@ func main() {
 	exe, args := os.Args[0], os.Args[1:]
 	exe = filepath.Base(exe)
 
-	if len(args) < 1 {
+	usage := func() {
 		fmt.Fprintf(os.Stderr, "usage: %s [file.riv] [file.html]\n", exe)
+	}
+
+	if len(args) < 1 {
+		usage()
 		return
 	}
 
 	inpath := args[0]
+	for _, arg := range args {
+		if arg == "-h" || arg == "--help" {
+			usage()
+			return
+		}
+	}
+
 	file, err := os.ReadFile(inpath)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "error reading file: %v\n", err)