在CentOS7上通过Yum Repository安装MySQL5.7.21

[root@GeekDevOps ~]# curl -O https://repo.mysql.com//mysql57-community-release-el7-11.noarch.rpm

[root@GeekDevOps ~]# yum -y localinstall mysql57-community-release-el7-11.noarch.rpm

[root@GeekDevOps ~]# yum repolist enabled|grep "mysql.*-community.*"
mysql-connectors-community/x86_64        MySQL Connectors Community           45
mysql-tools-community/x86_64             MySQL Tools Community                59
mysql57-community/x86_64                 MySQL 5.7 Community Server          247

[root@GeekDevOps ~]# yum -y install mysql-community-server

[root@GeekDevOps ~]# grep 'temporary password' /var/log/mysqld.log
2018-03-15T13:37:34.416639Z 1 [Note] A temporary password is generated for root@localhost: hbViaRqXw2;p

[root@GeekDevOps ~]# systemctl start mysqld

[root@GeekDevOps ~]# mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.21
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> set password=password('test123');
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements
mysql> set password =password('GeekDevOps../8');
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> quit

mysql> set global validate_password_mixed_case_count=0;  
Query OK, 0 rows affected (0.00 sec)  
mysql> set global validate_password_number_count=3;  
Query OK, 0 rows affected (0.00 sec)  
mysql> set global validate_password_special_char_count=0;  
Query OK, 0 rows affected (0.00 sec)  
mysql> set global validate_password_length=3;  
Query OK, 0 rows affected (0.00 sec)  
mysql> SHOW VARIABLES LIKE 'validate_password%'; 

[root@GeekDevOps ~]# yum -y remove mysql57-community-release-el7-11.noarch
[root@GeekDevOps ~]# rm mysql57-community-release-el7-11.noarch.rpm 

[root@GeekDevOps ~]# systemctl enable mysqld

[root@GeekDevOps ~]# mysql_secure_installation 

Securing the MySQL server deployment.

Enter password for user root: 
The 'validate_password' plugin is installed on the server.
The subsequent steps will run with the existing configuration
of the plugin.
Using existing password for root.

Estimated strength of the password: 100 
Change the password for root ? ((Press y|Y for Yes, any other key for No) : n

 ... skipping.
By default, a MySQL installation has an anonymous user,
allowing anyone to log into MySQL without having to have
a user account created for them. This is intended only for
testing, and to make the installation go a bit smoother.
You should remove them before moving into a production
environment.

Remove anonymous users? (Press y|Y for Yes, any other key for No) : y
Success.

Normally, root should only be allowed to connect from
'localhost'. This ensures that someone cannot guess at
the root password from the network.

Disallow root login remotely? (Press y|Y for Yes, any other key for No) : y
Success.

By default, MySQL comes with a database named 'test' that
anyone can access. This is also intended only for testing,
and should be removed before moving into a production
environment.

Remove test database and access to it? (Press y|Y for Yes, any other key for No) : y
 - Dropping test database...
Success.

 - Removing privileges on test database...
Success.

Reloading the privilege tables will ensure that all changes
made so far will take effect immediately.

Reload privilege tables now? (Press y|Y for Yes, any other key for No) : y
Success.

All done! 

[root@GeekDevOps system]# finger -l mysql
Login: mysql                    Name: MySQL Server
Directory: /var/lib/mysql               Shell: /bin/false
Never logged in.
No mail.
No Plan.

[root@GeekDevOps /]# ps -ef |grep mysql
mysql      2835      1  0 21:37 ?        00:00:05 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
root      12050   2606  0 23:07 pts/0    00:00:00 mysql -u root -p
root      12144  12055  0 23:46 pts/1    00:00:00 grep --color=auto mysql

[root@GeekDevOps /]# cat /usr/lib/systemd/system/mysqld.service |grep -e 'User' -e 'Group'
User=mysql
Group=mysql