Mysql安装

安装：忘记咋安装了，反正安装的版本是8.0.25
出现了以下问题 mark一下：

1. 启动失败，先去确认启动失败,查看端口起来没：

lsof -i 3306

2. 如果没有，则查看mysql的状态：

service mysqld status

3. 当发现启动失败，即出现failed to start mysql的文段，
4. 先重启看看：

systemctl restart mysqld.service

5. 执行journalctl -xe查看文档。报错：

Failed to start MySQL Server.
Unit mysqld.service entered failed state.

6. 根据博客 ：

# 修改/etc/my.cnf的datadir配置项
# 默认的是：

datadir=/var/lib/mysql
# 在 /var/lib/mysql创建个data目录 datadir改成
datadir=/var/lib/mysql/data

7. 再次登录发现，不记得密码,具体现象如下:

[root@VM-4-17-centos etc]# sudo mysql -uroot -p
Enter password: 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
[root@VM-4-17-centos etc]# sudo mysql -uroot -proot
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
[root@VM-4-17-centos etc]# sudo mysql -uroot -p
Enter password: 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
[root@VM-4-17-centos etc]# sudo mysql 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
[root@VM-4-17-centos etc]# mysqld -console --skip-grant-tables --shared-memory
2022-03-24T16:21:51.399204Z 0 [System] [MY-010116] [Server] /usr/local/mysql-8.0/bin/mysqld (mysqld 8.0.25) starting as process 24925
2022-03-24T16:21:51.402833Z 0 [ERROR] [MY-010123] [Server] Fatal error: Please read "Security" section of the manual to find out how to run mysqld as root!
2022-03-24T16:21:51.402893Z 0 [ERROR] [MY-010119] [Server] Aborting
2022-03-24T16:21:51.403171Z 0 [System] [MY-010910] [Server] /usr/local/mysql-8.0/bin/mysqld: Shutdown complete (mysqld 8.0.25)  MySQL Community Server - GPL.
[root@VM-4-17-centos etc]# mysqld 
2022-03-24T16:22:05.531085Z 0 [System] [MY-010116] [Server] /usr/local/mysql-8.0/bin/mysqld (mysqld 8.0.25) starting as process 24975
2022-03-24T16:22:05.534526Z 0 [ERROR] [MY-010123] [Server] Fatal error: Please read "Security" section of the manual to find out how to run mysqld as root!
2022-03-24T16:22:05.534577Z 0 [ERROR] [MY-010119] [Server] Aborting
2022-03-24T16:22:05.534798Z 0 [System] [MY-010910] [Server] /usr/local/mysql-8.0/bin/mysqld: Shutdown complete (mysqld 8.0.25)  MySQL Community Server - GPL.
[root@VM-4-17-centos etc]# service mysqld restart
Redirecting to /bin/systemctl restart mysqld.service

再看发现Mysql8.0默认生成随机密码，然后你进去需要修改密码，先去日志找密码：

find / -name mysqld.log
cd /var/log/
cat mysqld.log 

根据密码登陆，然后修改密码：

# ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
alter user user() identified by '123456';
# ERROR 1819 (HY000): Your password does not satisfy the current policy requirements
alter user user() identified by '?????';

修改密码完成。 成功可以登陆

其他问题

由于Mysql在有时会出现mysql.sock定位误差，会造成不连接数据库。
mac由当时的误差：
第一个变化my.cnf
位置/etc/my.cnf下一个，如果没有，那么。跟/usr/locate/mysql号/my.cnf下改动，然后拷贝到/etc下。
改动为例如以下：

[client]
socket = /tmp/mysql.sock
[mysqld]
socket = /tmp/mysql.sock

没有[client]的话。自己加入~