Fixed #884

cmd/yggdrasil/main.go

@@ -289,7 +289,12 @@ func run(args yggArgs, ctx context.Context, done chan struct{}) {
 		return
 	default:
 		// No flags were provided, therefore print the list of flags to stdout.
+		fmt.Println("Usage:")
 		flag.PrintDefaults()
+
+		if args.getaddr || args.getsnet {
+			fmt.Println("\nError: You need to specify some config data using -useconf or -useconffile.")
+		}
 	}
 	// Have we got a working configuration? If we don't then it probably means
 	// that neither -autoconf, -useconf or -useconffile were set above. Stop