更改登录密码：

有权限账号能登录mysql中：

修改当前用户密码

set password=password('redhat');    

有权限账号不能登录mysql中：

先停mysql,修改配置文件my.cnf

systemctl stop mariadb  #停止mysql
vim /etc/my.cnf   #更改配置文件

在mysqld下新增一行 skip-grant-tables

[mysqld]
skip-grant-tables

重启mysql

systemctl start mariadb

mysql 空密码进入

mysql -uroot

进入mysql库，查看user表：

use mysql;

select Host,User,Password from mysql.user; 

添加密码：

grant all on *.* to root@localhost identified by '123456' with grant option; 

mysql5.6版本命令

update mysql.user set password=password('123456') where user='root';
flush privileges; #刷新
exit

mysql5.7版本命令

update user set authentication_string=password('123456') where user='root' and Host='localhost';
flush privileges; #刷新
exit

修改密码8.0版本

新搭建好的mysql,查看默认密码，如没有则单机登录到mysql

cat /var/log/mysqld.log | grep localhost  

更改密码为空即‘mima’处无内容，即为免密（亦可设置你习惯的密码，就不是免密了）

alter user 'root'@'localhost' identified by 'mima';
flush privileges;
exit

改完后：

vim /etc/my.cnf

#skip-grant-tables  #注释 

重启mysql服务

systemctl restart mariadb 

mysql登录不上了

大概率是装有其他mysql，默认是在/tmp/mysql.sock
报错信息如下：

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

查找到mysqld.sock 对应位置添加软连接

ps -ef | grep mysql

rm /var/run/mysqld/mysqld.sock
ln -s /tmp/mysql.sock /var/run/mysqld/mysqld.sock

重启mysql

service mysqld restart 

本机安装了5.6后，又安装了mysql8.0

ubuntu22 发现有多个mysql 导致未找到mysqld.sock

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

进行删除

dpkg -l | grep mysql
#ii  mysql-client-core-8.0                  8.0.37-0ubuntu0.22.04.3                 amd64        MySQL database core client binaries
apt-get remove mysql-client-core-8.0

重启mysql恢复

systemctl  status mysql