[root@oraserver139 ~]# mysql -uroot -p
Enter password: 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

查看当前安装的mysql版本:
root@oraserver139 ~]# rpm -qa | grep MySQL
MySQL-server-5.6.15-1.el6.x86_64
MySQL-client-5.6.15-1.el6.x86_64
MySQL-shared-compat-5.6.15-1.el6.x86_64



停止mysql服务:
[root@oraserver139 ~]# service mysql stop
Shutting down MySQL.. SUCCESS! 

进入到skip-grant-tables模式:

[root@oraserver139 ~]# mysqld_safe --skip-grant-tables
140211 15:37:49 mysqld_safe Logging to '/var/lib/mysql/oraserver139.err'.
140211 15:37:49 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql


现在就不需要密码就可以进入mysql了:

[root@oraserver139 ~]# mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.6.15 MySQL Community Server (GPL)

Copyright (c) 2000, 2013, 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.

进入mysql系统数据库:
mysql> use mysql
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed

修改root账户密码:
mysql> update user set password=password("12345") where user="root";
Query OK, 4 rows affected (0.02 sec)
Rows matched: 4 Changed: 4 Warnings: 0


刷新权限:
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql> exit
Bye


停止mysql进程:

[1]+ Stopped mysqld_safe --skip-grant-tables

启动mysql:

[root@oraserver139 ~]# service mysql start
Starting MySQL SUCCESS! 


使用刚才修改的密码进入mysql:

[root@oraserver139 ~]# mysql -uroot -p12345
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.6.15

Copyright (c) 2000, 2013, 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> show databases;
ERROR 1820 (HY000): You must SET PASSWORD before executing this statement

mysql> SET PASSWORD = PASSWORD('12345');
Query OK, 0 rows affected (0.00 sec)

mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.00 sec)

修改完成;linux