On RHEL and CentOS, MySQL does not set a root password by default. MySQL does not set a root password by default. It is very strongly recommended to set a root password as a security precaution.
[root@cloudstack etc]# mysql -u root
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.1.61-log Source distribution
Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the current input statement.
mysql> SET PASSWORD = PASSWORD(‘admin’);
Query OK, 0 rows affected (0.00 sec)
mysql> exit
Bye
[root@cloudstack etc]# mysql -u root -padmin
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.1.61-log Source distribution
Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the current input statement.
mysql>
Done!!