Startup options, fixed new group bug with unnamed groups

main.go

@@ -3,26 +3,51 @@ package main
 import (
 	"encoding/json"
 	"fmt"
+	"flag"
 	"os"
+	"strings"
 )
 
 func main() {
-	if len(os.Args) < 2 {
-		fmt.Fprintf(os.Stderr, "filename required\n")
-		os.Exit(1)
+	configPath := flag.String("config", "", "path to configuration file")
+
+	flag.Parse()
+
+	if *configPath == "" {
+		if _, err := os.Stat("./alrmrc"); err == nil {
+			*configPath = "./alrmrc"
+		}
+		if _, err := os.Stat("/etc/alrmrc"); err == nil {
+			*configPath = "/etc/alrmrc"
+		}
+		if *configPath == "" {
+			fmt.Fprintf(os.Stderr, "Cannot find configuration\n")
+			os.Exit(1)
+		}
 	}
 
-	config, err := ReadConfig(os.Args[1])
+	config, err := ReadConfig(*configPath)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "%s\n", err.Error())
 		os.Exit(1)
 	}
 
-	o, err := json.Marshal(config)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "JSON error: %s\n", err.Error())
-		os.Exit(1)
-	}
+	command := strings.ToLower(flag.Arg(0))
+	switch command {
+		case "json":
+			o, err := json.MarshalIndent(config, "", "  ")
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "JSON error: %s\n", err.Error())
+				os.Exit(1)
+			}
+			fmt.Fprintf(os.Stdout, "%s", string(o))
 
-	fmt.Println(string(o))
+		case "", "config":
+			fmt.Fprintf(os.Stdout, "Config is OK.\n")
+			os.Exit(0)
+
+		default:
+			fmt.Fprintf(os.Stderr, "Unknown command: %s\n", command)
+			os.Exit(1)
+	}
 }