安装环境：OS：Centos 7.9
已经安装的Mysql：Mysql 8.0.26 安装目录:/usr/local/mysql
需要安装的Mysql版本：Mysql 5.7.35
多版本安装思路：Mysql安装目录、数据文件目录、pid文件、socket文件，监听端口，配置文件等都设置不同的位置。
1.安装过程：
先前的安装，已经建立了OS用户和环境变量，本次安装就可以略过这些步骤。
1.1 解压安装包
cd /usr/local
tar zxvf mysql-5.7.35-el7-x86_64.tar.gz -C /usr/local/
mv mysql-5.7.35-el7-x86_64 mysql-5.7.35
cd /usr/local/mysql-5.7.35
mkdir mysql-files run log
touch log/mysqld.log
chown -R mysql:mysql /usr/local/mysql /usr/local/mysql-5.7.35 /data/mysql5.7
chmod 750 mysql-files
1.2 建Mysql配置文件
vi /usr/local/mysql-5.7.35/my.cnf [client] port = 3307 default-character-set=utf8 [mysqld] default-storage-engine=innodb innodb_file_per_table=1 innodb_flush_log_at_trx_commit=1 max_allowed_packet=16M character_set_server=utf8 port = 3307 max_connections=2000 init_connect='SET NAMES utf8' basedir=/usr/local/mysql-5.7.35 datadir=/data/mysql5.7 socket=/usr/local/mysql-5.7.35/mysql.sock log-error=/usr/local/mysql-5.7.35/log/mysqld.log pid-file=/usr/local/mysql-5.7.35/run/mysqld.pid #bin log server_id=101 log-bin=/usr/local/mysql-5.7.35/log/product-bin slave-skip-errors=all skip-slave-start=1 relay_log=mysql-relay-bin expire_logs_days=10 #slow query log slow_query_log=1 slow_query_log_file=/usr/local/mysql-5.7.35/log/slow_query.log lower_case_table_names = 1 [mysqld_safe] lower_case_table_names = 1 log-error=/usr/local/mysql-5.7.35/log/mysqld.log pid-file=/usr/local/mysql-5.7.35/run/mysqld.pid
1.3 初始化Mysql
bin/mysqld --defaults-file=/usr/local/mysql-5.7.35/my.cnf --initialize --user=mysql --basedir=/usr/local/mysql-5.7.35 --datadir=/data/mysql5.7 --console --lower-case-table-names=1
初始化时指定Mysql配置文件。
1.4 启动Mysql
通过support-files下面的myslq.server命令启动Mysql 5.7。
也可以通过配置/etc/systemd/system/mysqld5.7.service，使用systemctl工具来管理Mysql服务的启停。
vi /etc/systemd/system/mysqld5.7.service [Unit] Description=MySQL Server Documentation=man:mysqld(8) Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html After=network.target After=syslog.target [Install] WantedBy=multi-user.target [Service] User=mysql Group=mysql ExecStart=/usr/local/mysql-5.7.35/bin/mysqld --defaults-file=/usr/local/mysql-5.7.35/my.cnf LimitNOFILE = 5000
1.4 连接Mysql
[root@Mysqltest support-files]# mysql -uroot -S /usr/local/mysql-5.7.35/mysql.sock -pXXXXXX
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 7
Server version: 5.7.35-log MySQL Community Server (GPL)
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
mysql>
注意：
1.输入的XXXXXX密码为初始化时产生的随机密码；
2.此处连接必须指定socket文件，才能正常连接到第二个Mysql实例。
第二个版本的Mysql安装完成。