centos7.5修改mysql5.7.24默认密码

mysql是yum安装的，版本为5.7.24

装完后启动mysql，会产生个随机密码在/var/log/mysqld.log文件中

mysql> select version();
+-----------+
| version() |
+-----------+
| 5.7.24    |
+-----------+
1 row in set (0.00 sec)

如下图：进去就报错，修改密码还是报错

[root@localhost ~]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.24

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> use mysql
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'qqq...';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements
mysql> show databases;
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

解决参考：http://blog.sina.com.cn/s/blog_a0d71a9d0102wlz3.html
在mysql中操作下面几条就可以了：

mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.01 sec)

mysql> set global validate_password_length=1;
Query OK, 0 rows affected (0.00 sec)

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'qqq...';
Query OK, 0 rows affected (0.01 sec)

mysql> quit
Bye
[root@localhost ~]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.