Linux环境下MySQL8.0安装

# 一、准备工作

下载安装包下载地址
查看系统⾃带的 MARIADB
```
rpm -qa|grep mariadb
```
卸载系统⾃带的 MARIADB（如果有）,remove后面加 rpm -qa|grep mariadb 查询出来的路径
```
yum -y remove
```

# 二、解压

将 mysql-8.0.26-linux-glibc2.12-x86_64.tar.xz 安装包上传到 /usr/local/ 目录下

安装包解压,并重命名为mysql

xz -d mysql-8.0.26-linux-glibc2.12-x86_64.tar.xz
tar -xvf mysql-8.0.26-linux-glibc2.12-x86_64.tar 
mv mysql-8.0.26-linux-glibc2.12-x86_64 mysql

创建MYSQL⽤户和⽤户组
```
groupadd mysql
useradd -g mysql mysql
```
修改MYSQL⽬录的归属⽤户
```
chown -R mysql:mysql ./
```

准备MYSQL的配置⽂件,编辑 vim /etc/my.cnf

[mysql]
# 设置mysql客户端默认字符集
default-character-set=utf8
socket=/var/lib/mysql/mysql.sock
[mysqld]
skip-name-resolve
#设置3306端⼝
port = 3306
socket=/var/lib/mysql/mysql.sock
# 设置mysql的安装⽬录
basedir=/usr/local/mysql
# 设置mysql数据库的数据的存放⽬录
datadir=/usr/local/mysql/data
# 允许最⼤连接数
max_connections=200
# 服务端使⽤的字符集默认为8⽐特编码的latin1字符集
character-set-server=utf8
# 创建新表时将使⽤的默认存储引擎
default-storage-engine=INNODB
lower_case_table_names=1
max_allowed_packet=16M
# binglog配置
server-id = 1
log-bin = mysql-bin
log_bin_index = binlog.index
binlog_format = ROW
# binlog过期清理时间；
expire_logs_days= 7
# binlog每个日志文件大小；
max_binlog_size = 1024m
# binlog缓存大小；
binlog_cache_size = 128m
# 最大binlog缓存大小。
max_binlog_cache_size = 1024m

并且修改权限

mkdir /var/lib/mysql 
chmod 777 /var/lib/mysql

# 三、安装MySQL

进入cd /usr/local/mysql 目录进行初始化

./bin/mysqld --initialize --user=mysql --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data

执行初始化后,控制台会返回临时密码, 记录临时密码 ,后面会用到
例如:像我的例子在最后一行 A temporary password is generated for root@localhost:kvct:yIy8_qk
我的临时密码就是这个: kvct:yIy8_qk

例子:
2021-09-14T01:30:19.227943Z 0 [System] [MY-013169] [Server] /usr/local/mysql/bin/mysqld (mysqld 8.0.26) initializing of server in progress as process 1808
2021-09-14T01:30:19.250431Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2021-09-14T01:30:20.184005Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
2021-09-14T01:30:21.140583Z 0 [Warning] [MY-013746] [Server] A deprecated TLS version TLSv1 is enabled for channel mysql_main
2021-09-14T01:30:21.141148Z 0 [Warning] [MY-013746] [Server] A deprecated TLS version TLSv1.1 is enabled for channel mysql_main
2021-09-14T01:30:21.341903Z 6 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: kvct:yIy8_qk

复制启动脚本到资源目录

cp ./support-files/mysql.server /etc/init.d/mysqld

编辑vim /etc/init.d/mysqld ,修改 basedir 和 datadir ,为其实际对应的目录
```
basedir=/usr/local/mysql 
datadir=/usr/local/mysql/data
```

# 四、设置MYSQL服务开机自启

增加 mysqld 服务控制脚本执⾏权限
```
chmod +x /etc/init.d/mysqld
```
将 mysqld 服务加⼊到系统服务
```
chkconfig --add mysqld
```
检查 mysqld 服务是否已经⽣效即可
mysqld 0:关 1:关 2:开 3:开 4:开 5:开 6:关
```
chkconfig --list mysqld
```
启动 mysql 服务, 返回 SUCCESS!
```
service mysqld start
```
如何停止 mysql 服务
```
 service mysqld stop
```
# 五、配置环境变量
编辑 vim ~/.bash_profile,在文件末尾添加下面信息
```
export PATH=$PATH:/usr/local/mysql/bin
```
执行下面命令,使环境变量生效
```
source ~/.bash_profile
```

# 六、登录MySQL，并修改密码

以 root 账户登录 mysql
```
mysql -u root -p
```
输入刚才记录的 临时密码

修改 Root 账户密码,并刷新权限

alter user user() identified by "root";
flush privileges;

设置远程主机登录

use mysql;
update user set user.Host='%' where user.User='root';
flush privileges;

# 七、检查防火墙

做完上面步骤,肯能还是远程连接不上,开放端口或者关闭防火墙
查看防火墙状态
```
systemctl status firewalld
```
查看开机是否启动防火墙服务
```
systemctl is-enabled firewalld
```
关闭防火墙
```
systemctl stop firewalld
```

禁用防火墙（系统启动时不启动防火墙服务）

systemctl disable firewalld
systemctl is-enabled firewalld

开放端口

firewall-cmd --zone=public --add-port=3306/tcp --permanent
firewall-cmd --reload   # 配置立即生效

关闭端口

firewall-cmd --zone=public --remove-port=3306/tcp --permanent
firewall-cmd --reload   # 配置立即生效

查看防火墙所有开放的端口

firewall-cmd --zone=public --list-ports

查看监听的端口
centos7默认没有 netstat 命令，需要安装 net-tools 工具，yum install -y net-tools
```
netstat -lnpt
```
检查端口被哪个进程占用

```
netstat -lnpt |grep 3306
```

查看进程的详细信息

```
ps 6832
```

查看包含 mysql 的所有进程

```
ps -ef | grep mysql
```

中止进程

```
kill -9 6832
```

# 八、忘记 `mysql` 密码, 找回密码

停止 mysql 服务
```
 service mysqld stop
```
修改 mysql 的配置文件 my.cnf
my.cnf 配置文件的位置，一般在 /etc/my.cnf ，有些版本在 /etc/mysql/my.cnf
在配置文件中添加下面代码, 安全模式启动
```
[mysqld]
skip-grant-tables
```
启动 mysql 服务
```
service mysqld start
```

进入 mysql, 这样可以不用输入密码进入 mysql

mysql -u root

修改密码, 并刷新权限;

mysql> use mysql;
Database changed
mysql> update user set authentication_string="123456" where user="root";
Query OK, 0 rows affected (0.00 sec)
Rows matched: 1  Changed: 0  Warnings: 0
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

将刚才新添加的配置文件 my.cnf 删除这两行
```
[mysqld]
skip-grant-tables
```

重新启动 mysql 服务

service mysqld start

MYSQL 8.0 默认user表

mysql> select host, user, authentication_string, plugin from user;
+-----------+------------------+------------------------------------------------------------------------+-----------------------+
| host      | user             | authentication_string                                                  | plugin                |
+-----------+------------------+------------------------------------------------------------------------+-----------------------+
| %         | root             | $A$005$_N6
HbERn<n&lg8k*XmaW25XLFVs8MDOgM1K18egNm1p87ttKMQ9Awcf0/rUA  | caching_sha2_password |
| localhost | mysql.infoschema | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| localhost | mysql.session    | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| localhost | mysql.sys        | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
+-----------+------------------+------------------------------------------------------------------------+-----------------------+

# 九、Access denied for user 'root'@'localhost' (using password: YES)

安全模式启动 mysql服务,先将密码设置为空

use mysql;
update user set authentication_string='' where user='root';

在重新设置密码, 刷新权限

use mysql;
alter user user() identified by "root";
flush privileges;

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