MySQL 8.0 以上版本重置 root 用户密码

1. 在 /etc/my.cnf 文件末尾追加 skip-grant-tables

   [root@abdefg mysql]# vim /etc/my.cnf
   [mysql]
   # 设置mysql客户端默认字符集
   default-character-set=utf8mb4
   
   [mysqld]
   # 设置3306端口
   port = 3306
   # 设置mysql的安装目录
   basedir=/usr/local/mysql
   # 设置mysql数据库的数据的存放目录
   datadir=/usr/local/mysql/data
   # 允许最大连接数
   max_connections=200
   # 服务端默认编码（数据库级别）
   character-set-server=utf8mb4
   # 创建新表时将使用的默认存储引擎
   default-storage-engine=INNODB
   lower_case_table_names=1
   max_allowed_packet=16M
   skip-grant-tables

2. 重启MySQL服务

   [root@abdefg mysql]# service mysqld restart

3. 免密码登录 root 用户（输入密码时直接回车即可）

   [root@abdefg bin]# mysql -uroot -p
   Enter password:
   Welcome to the MySQL monitor.  Commands end with ; or \g.
   Your MySQL connection id is 8
   Server version: 8.0.13 MySQL Community Server - GPL
   
   Copyright (c) 2000, 2018, 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>

4. 重置密码

   mysql> use mysql

   查询一下

   mysql> select host, user, authentication_string, plugin from user;

   执行修改报错

   mysql> alter user 'root'@'localhost'IDENTIFIED BY 'newpassword[@123](https://my.oschina.net/u/9520)';
   ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement

   先执行flush privileges;然后会alter成功，要不然会alter失败

   mysql> flush privileges;
   Query OK, 0 rows affected (0.00 sec)
   
   mysql> alter user 'root'@'localhost'IDENTIFIED BY 'newpassword[@123](https://my.oschina.net/u/9520)';
   Query OK, 0 rows affected (0.03 sec)
   
   mysql> exit
   Bye

5. 把/etc/my.cnf 文件末尾的 skip-grant-tables 去掉，重启MySQL服务，修改完成

参考文档：网络蚂蚁 奥斯维克鸡腿学徒