don't receive any error unless no right to do backup

[BRUNO MATRINGHEN]

Hi everybody,

I'm newbie in MySQL unless I'm DBA on DB2, SYBASE IQ, ORACLE...
I'm testing mysqldump to backup my mysql databases.
I'm working with "5.6.10 MySQL Community Server (GPL)" and with "MySQL dump 10.13 Distrib 5.6.10, for linux-glibc2.5 (x86_64)"

I've create a mysql user which name is backupdb@localhost.
I've the password in a /root/.my.cnf file to hide the password :
[mysqldump]
user = backupdb
host = localhost
password = xxxx

The user has only those privileges :
GRANT USAGE ON *.* TO 'backupdb'@'localhost'

So I'm testing the return code of the mysqldump in order to cath it.

I'm doing this to do backup :
/usr/local/mysql/bin/mysqldump --opt --quick --max_allowed_packet=64M --protocol=SOCKET --socket=/data/mysql-datadir/instance-dev.sock --all-databases
which return 0 and this output :
-- MySQL dump 10.13 Distrib 5.6.10, for linux-glibc2.5 (x86_64)
--
-- Host: localhost Database:
-- ------------------------------------------------------
-- Server version 5.6.10

/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;

/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;

-- Dump completed on 2013-06-12 10:21:57

Has someone an explication ?
Why don't I receive a RC=2 ?

Bruno