/etc/init.d/mysql stop
2. 接着采用忽略密码认证模式重新创建一个mysql服务
mysqld --user=mysql --skip-grant-tables --skip-networking &
成功启动后返回PID及其它启动信息
[1] 3591 root@webserver:/home/webmaster# 121005 2:59:27 [Note] Plugin ‘FEDERATED‘ is disabled. 121005 2:59:27 InnoDB: The InnoDB memory heap is disabled 121005 2:59:27 InnoDB: Mutexes and rw_locks use GCC atomic builtins 121005 2:59:27 InnoDB: Compressed tables use zlib 1.2.3.4 121005 2:59:27 InnoDB: Initializing buffer pool, size = 128.0M 121005 2:59:27 InnoDB: Completed initialization of buffer pool 121005 2:59:27 InnoDB: highest supported file format is Barracuda. 121005 2:59:27 InnoDB: Waiting for the background threads to start 121005 2:59:28 InnoDB: 1.1.8 started; log sequence number 1595685 121005 2:59:28 [Note] mysqld: ready for connections. Version: ‘5.5.24-0ubuntu0.12.04.1‘ socket: ‘/var/run/mysqld/mysqld.sock‘ port: 0 (Ubuntu)
3. 连接到mysql系统库
mysql -u root mysql
4. 连接到mysql库后直接修改root账号的密码为新的密码‘123456‘
Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement. mysql> update user set Password=PASSWORD(‘123456‘) where user=‘root‘; Query OK, 3 rows affected (0.00 sec) Rows matched: 3 Changed: 3 Warnings: 0 mysql> FLUSH PRIVILEGES; mysql> quit; Bye
5. 中止mysql服务进程
kill 3591
6.正常启动mysql服务，并用新密码登录mysql服务器
service mysql start
原文：http://www.cnblogs.com/longzhongren/p/4349551.html