修改MySQL root 用户密码：

编辑配置文件 /etc/my.cnf，在 mysqld 下添加 skip-grant-tables：

[mysqld]
skip-grant-tables

重启MySQL服务：

[root@JT-T-KEYAN-001 ~]# service mysqld restart
Shutting down MySQL....                                    [确定]
Starting MySQL.                                            [确定]
[root@JT-T-KEYAN-001 ~]#

直接输入 mysql 进入

[root@JT-T-KEYAN-001 ~]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.31 MySQL Community Server (GPL)

Copyright (c) 2000, 2020, 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>

切换到 mysql 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
mysql>

修改密码并退出：

mysql> update user set authentication_string=password('your_password') where user = 'root';
Query OK, 2 rows affected, 1 warning (0.00 sec)
Rows matched: 2  Changed: 2  Warnings: 0

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> exit
Bye
[root@JT-T-KEYAN-001 ~]#

删除配置文件中添加的skip-grant-tables，重启MySQL服务：

[root@JT-T-KEYAN-001 ~]# service mysqld restart
Shutting down MySQL..                                      [确定]
Starting MySQL.                                            [确定]
[root@JT-T-KEYAN-001 ~]#