[root@instance-r5y0pf5d ~]# mysqld --help --verbose|grep "my.cnf"
2021-01-07T01:43:46.831576Z 0 [Note] --secure-file-priv is set to NULL. Operations related to importing and exporting data are disabled
2021-01-07T01:43:46.831666Z 0 [Note] mysqld (mysqld 5.7.26) starting as process 28770 ...
2021-01-07T01:43:46.926752Z 0 [Note] Plugin ‘FEDERATED‘ is disabled.
/etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql/etc/my.cnf ~/.my.cnf 
2021-01-07T01:43:46.937792Z 0 [Note] Binlog end
2021-01-07T01:43:46.937853Z 0 [Note] Shutting down plugin ‘MyISAM‘
2021-01-07T01:43:46.937870Z 0 [Note] Shutting down plugin ‘CSV‘
                      my.cnf, $MYSQL_TCP_PORT, /etc/services, built-in default
[root@instance-r5y0pf5d ~]# 

[mysqld]服务端
user=mysql用户名
basedir=/application/mysql软件路径
datadir=/data/mysql/data数据路径
socket=/tmp/mysql.sock本地启动文件路径
server_id=6大于1的任意数定义为服务区id
port=3306设置服务端口
log_error=/data/mysql/data/mysql.log错误日志路径
log_bin=/data/mysql/data/mysql-bin二进制错误日志路径
[mysql]客户端
socket=/tmp/mysql.sock客户端连接文件的路径

[root@instance-r5y0pf5d ~]# mkdir -p /data/330{7,8,9}/data
[root@instance-r5y0pf5d ~]# cat > /data/3307/my.cnf <<EOF
> [mysqld]
> basedir=/application/mysql
> datadir=/data/3307/data
> socket=/data/3307/mysql.sock
> log_error=/data/3307/mysql.log
> log_bin=/data/3307/mysql-bin
> port=3307
> server_id=7
> EOF
[root@instance-r5y0pf5d ~]# cat > /data/3308/my.cnf <<EOF
> [mysqld]
> basedir=/application/mysql
> datadir=/data/3308/data
> socket=/data/3308/mysql.sock
> log_error=/data/3308/mysql.log
> log_bin=/data/3308/mysql-bin
> port=3308
> server_id=8
> EOF
[root@instance-r5y0pf5d ~]# cat > /data/3309/my.cnf <<EOF
> [mysqld]
> basedir=/application/mysql
> datadir=/data/3309/data
> socket=/data/3309/mysql.sock
> log_error=/data/3309/mysql.log
> log_bin=/data/3309/mysql-bin
> port=3309
> server_id=9
> EOF
[root@instance-r5y0pf5d ~]# 

[root@instance-r5y0pf5d ~]# mv /etc/my.cnf /etc/my.cnf.bak
[root@instance-r5y0pf5d ~]# mysqld --initialize-insecure --user=mysql --datadir=/data/3307/data --basedir=/application/mysql
2021-01-07T03:21:29.659913Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2021-01-07T03:21:30.629030Z 0 [Warning] InnoDB: New log files created, LSN=45790
2021-01-07T03:21:30.766470Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2021-01-07T03:21:30.876554Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 6fac189f-5097-11eb-9415-fa270000fffa.
2021-01-07T03:21:30.878375Z 0 [Warning] Gtid table is not ready to be used. Table ‘mysql.gtid_executed‘ cannot be opened.
2021-01-07T03:21:30.878744Z 1 [Warning] root@localhost is created with an empty password ! Please consider switching off the --initialize-insecure option.
[root@instance-r5y0pf5d ~]# 

[root@instance-r5y0pf5d ~]# mysqld --initialize-insecure --user=mysql --datadir=/data/3308/data --basedir=/application/mysql
2021-01-07T03:24:25.261579Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2021-01-07T03:24:26.224140Z 0 [Warning] InnoDB: New log files created, LSN=45790
2021-01-07T03:24:26.366712Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2021-01-07T03:24:26.431231Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: d84f9d98-5097-11eb-9a84-fa270000fffa.
2021-01-07T03:24:26.433115Z 0 [Warning] Gtid table is not ready to be used. Table ‘mysql.gtid_executed‘ cannot be opened.
2021-01-07T03:24:26.433459Z 1 [Warning] root@localhost is created with an empty password ! Please consider switching off the --initialize-insecure option.
[root@instance-r5y0pf5d ~]#

 

[root@instance-r5y0pf5d ~]# mysqld --initialize-insecure --user=mysql --datadir=/data/3309/data --basedir=/application/mysql
2021-01-07T03:27:16.339676Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2021-01-07T03:27:17.305843Z 0 [Warning] InnoDB: New log files created, LSN=45790
2021-01-07T03:27:17.442117Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2021-01-07T03:27:17.510814Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 3e4849b8-5098-11eb-a219-fa270000fffa.
2021-01-07T03:27:17.512752Z 0 [Warning] Gtid table is not ready to be used. Table ‘mysql.gtid_executed‘ cannot be opened.
2021-01-07T03:27:17.513095Z 1 [Warning] root@localhost is created with an empty password ! Please consider switching off the --initialize-insecure option.
[root@instance-r5y0pf5d ~]#

[root@instance-r5y0pf5d ~]# cd /etc/systemd/system
[root@instance-r5y0pf5d /etc/systemd/system]# cp mysqld.service mysqld3307.service
[root@instance-r5y0pf5d /etc/systemd/system]# cp mysqld.service mysqld3308.service
[root@instance-r5y0pf5d /etc/systemd/system]# cp mysqld.service mysqld3309.service
[root@instance-r5y0pf5d /etc/systemd/system]# vim mysqld3307.service
[root@instance-r5y0pf5d /etc/systemd/system]# tail -n 2 mysqld3307.service
ExecStart=/application/mysql/bin/mysqld --defaults-file=/data/3307/my.cnf
LimitNOFILE = 5000
[root@instance-r5y0pf5d /etc/systemd/system]# vim mysqld3308.service
[root@instance-r5y0pf5d /etc/systemd/system]# tail -n 2 mysqld3308.service|head -n1
ExecStart=/application/mysql/bin/mysqld --defaults-file=/data/3308/my.cnf
[root@instance-r5y0pf5d /etc/systemd/system]# vim mysqld3309.service
[root@instance-r5y0pf5d /etc/systemd/system]# tail -n 2 mysqld3309.service|head -n1
ExecStart=/application/mysql/bin/mysqld --defaults-file=/data/3309/my.cnf
[root@instance-r5y0pf5d /etc/systemd/system]# 

[root@instance-r5y0pf5d /etc/systemd/system]# chown -R mysql.mysql /data/*
[root@instance-r5y0pf5d /etc/systemd/system]# systemctl start mysqld3307.service
[root@instance-r5y0pf5d /etc/systemd/system]# systemctl start mysqld3308.service
[root@instance-r5y0pf5d /etc/systemd/system]# systemctl start mysqld3309.service

[root@instance-r5y0pf5d ~]# netstat -lnp|grep 330
tcp6 0 0 :::3307 :::* LISTEN 31843/mysqld
tcp6 0 0 :::3308 :::* LISTEN 31877/mysqld
tcp6 0 0 :::3309 :::* LISTEN 364/mysqld
unix 2 [ ACC ] STREAM LISTENING 709710 31843/mysqld /data/3307/mysql.sock
unix 2 [ ACC ] STREAM LISTENING 709992 31877/mysqld /data/3308/mysql.sock
unix 2 [ ACC ] STREAM LISTENING 727558 364/mysqld /data/3309/mysql.sock
[root@instance-r5y0pf5d ~]#

[root@instance-r5y0pf5d /etc/systemd/system]# mysql -S /data/3307/mysql.sock -e "select @@server_id"
+-------------+
| @@server_id |
+-------------+
| 7 |
+-------------+
[root@instance-r5y0pf5d /etc/systemd/system]# mysql -S /data/3308/mysql.sock -e "select @@server_id"
+-------------+
| @@server_id |
+-------------+
| 8 |
+-------------+

[root@instance-r5y0pf5d ~]# mysql -S /data/3309/mysql.sock -e "select @@server_id"
+-------------+
| @@server_id |
+-------------+
| 9 |
+-------------+
[root@instance-r5y0pf5d ~]#