1、结束当前正在运行的mysql进程。
# /etc/init.d/mysql stop
2、用mysql安全模式运行并跳过权限验证。
# /usr/bin/mysqld_safe --skip-grant-tables
3、重开一个终端以root身份登录mysql。
# mysql -u root
4、修改root用户口令。
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 -ADatabase changed
mysql> update user set Password = PASSWORD('root') where User ='root';
Query OK, 3 rows affected (0.00 sec)Rows matched: 3 Changed: 3 Warnings: 0
mysql> exit
5、结束mysql安全模式，用正常模式运行mysql。
# /etc/init.d/mysql restart
6、试试你新修改的口令
mysql> show grants for 'root'@'127.0.0.1';
mysql> flush privileges；
mysql> quit;
转自：http://www.cnblogs.com/yuxc/archive/2012/07/25/2607587.html
