版本号：

mysql> status;
--------------
mysql  Ver 8.4.7 for Linux on x86_64 (MySQL Community Server - GPL)

Connection id:          7
Current database:
Current user:           root@
SSL:                    Not in use
Current pager:          stdout
Using outfile:          ''
Using delimiter:        ;
Server version:         8.4.7 MySQL Community Server - GPL
Protocol version:       10
Connection:             Localhost via UNIX socket
Server characterset:    utf8mb4
Db     characterset:    utf8mb4
Client characterset:    utf8mb4
Conn.  characterset:    utf8mb4
UNIX socket:            /var/run/mysqld/mysqld.sock
Binary data as:         Hexadecimal
Uptime:                 3 min 29 sec

Threads: 1  Questions: 8  Slow queries: 0  Opens: 131  Flush tables: 3  Open tables: 52  Queries per second avg: 0.038
--------------

mysql> 

关闭服务：

systemctl stop mysql
systemctl status mysql

使用免密码模式启动服务：

sudo mysqld --skip-grant-tables --skip-networking --user=mysql 

出现/var/lib/mysql 权限不够，修改

chown -R mysql:mysql /var/lib/mysql 

chmod -R 777 /var/lib/mysql

在另一个窗口进入mysql：

mysql -u root 

修改密码

FLUSH PRIVILEGES;
ALTER USER 'root'@'localhost' IDENTIFIED BY '新密码';
EXIT;

ctrl+C关闭mysql 免密码模式

重启服务器：

systemctl start mysql