환경

centos 7.x MySQL 5.7.20

전제

1.MySQL을 다시 시작할 수 있습니다

2.서버에 로그인할 수 있습니다

조작하다

1.원본 암호

[root@1]# mysql -uroot -p12345
mysql: [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 4
Server version: 5.7.20-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, 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.

(root@localhost) [(none)]>

2.비밀번호를 잊어버렸다고 가정해 보세요

- 1.  my.cnf
vim /etc/my.cnf //  
[mysqld]
skip-grant-tables //   my.cnf  

- 2.  MySQL
service mysqld restart //  
Shutting down MySQL.. SUCCESS!
Starting MySQL... SUCCESS!

3.암호를 수정합니다

[root@1]# mysql //  ， 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.20-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, 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.

(root@localhost) [(none)]> alter user 'root'@'localhost' identified by '123'; //   skip grant， 。
ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement

(root@localhost) [(none)]>flush PRIVILEGES; //  
Query OK, 0 rows affected (0.01 sec)

(root@localhost) [(none)]>alter user 'root'@'localhost' identified by '123'; //  
Query OK, 0 rows affected (0.00 sec)

(root@localhost) [(none)]>flush tables; //  
Query OK, 0 rows affected (0.00 sec)

(root@localhost) [(none)]>quit //  
Bye

4.성공 현상

[root@1]# mysql //  ，skip grant  
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

[root@1]# mysql -uroot -p123 //  ， 
mysql: [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 4
Server version: 5.7.20-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, 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.

(root@localhost) [(none)]>

주의: 설정 파일의skipgrant 주석을 지우기