CentOS7.4安装MySQL踩坑记录

CentOS7.4安装MySQL踩坑记录

time: 2018.3.19

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CentOS7.4安装MySQL时网上的文档虽然多可是不靠谱的也多, 可能由于版本与时间的问题, 因此记录下本身踩坑的过程, 若是你发现进坑了, 欢迎参考本篇文章:)

• 第一次尝试遇到的问题:

Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

尝试卸载从新安装, 参考, 步骤:

1.查看yum是否安装过mysql
yum list installed mysql*
yum list installed | grep mysql*
没有显示结果, 说明yum中没有安装mysql(对yum与rpm并非很了解, 若有错误欢迎指出)
2.删除配置文件与文件夹
rm -rf /var/lib/mysql
rm /etc/my.cnf
3.查看rpm中的安装并卸载
rpm -qa | grep -i mysql
如下根据上面命令显示的列表修改

rpm -e mysql-community-server-5.7.21-1.el7.x86_64 mysql-community-common-5.7.21-1.el7.x86_64 mysql-community-libs-5.7.21-1.el7.x86_64 mysql57-community-release-el7-11.noarch mysql-community-client-5.7.21-1.el7.x86_64  mysql-community-libs-compat-5.7.21-1.el7.x86_64 --nodeps

3.清除余项
whereis mysql
删除上面命令显示的路径
rm -rf /usr/share/mysql/
4.删除配置
rm -rf /usr/my.cnf
rm -rf /root/.mysql*# 无结果

# 笔者机器上无结果
chkconfig --list | grep -i mysql
chkconfig --del mysqld
systemctl list-dependencies | grep -i mysql

5.从新安装

下载mysql源并安装到rpm:

wget http://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm
rpm -ivh mysql57-community-release-el7-11.noarch.rpm

更新yum并安装mysql(时间较长):

# 更新yum软件包
yum check-update
# 更新系统
yum update
# 安装mysql
yum install mysql mysql-server

注意事项
更新yum后可能须要从新编辑/usr/bin/yum文件头(由于笔者将默认的python更改成python3), 编辑后再次安装便可, 出现的错误以下:

[root@centos ~]# yum install mysql mysql-server
  File "/usr/bin/yum", line 30
    except KeyboardInterrupt, e:
                            ^
SyntaxError: invalid syntax

安装完成后配置

未跳过grant-tables受权表时启动MySQL会出现:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

这里须要修改root的密码, 这条命令是给mysql加上一个启动参数--skip-grant-tables, 顾名思义,就是在启动mysql时不启动grant-tables受权表, 用于忘记管理员密码后的修改
/usr/local/mysql/bin/mysqld_safe --skip-grant-tables --user=mysql &
可是, MySQL 5.7.6 版本开始默认是不安装mysqld_safe了, 如下为新方法:
1.中止 mysql 服务
service mysqld stop
2.设置 mysqld 选项 --skip-grant-tables参数:
systemctl set-environment MYSQLD_OPTS='--skip-grant-tables'
3.从新启动mysql
systemctl start mysqld
4.执行 mysql -u root 登陆mysql并更改密码

[root@centos ~]# mysql -uroot
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.21 MySQL Community Server (GPL)

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

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> UPDATE mysql.user
    -> SET authentication_string = PASSWORD('toor'), password_expired = 'N'
    -> WHERE User = 'root' AND Host = 'localhost';
Query OK, 1 row affected, 1 warning (0.65 sec)
Rows matched: 1  Changed: 1  Warnings: 1

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql>

password_expired = 'N'过时状态设置为No, flush privileges; 刷新权限记录, 详见

5.设置完密码后去掉--skip-grant-tables参数, 重启mysql便可用设置的密码登陆root用户
systemctl unset-environment MYSQLD_OPTS
systemctl restart mysqld
mysql -uroot -p

MySQL5.7开启远程链接

1.链接到mysql数据库
mysql -uroot -p
2.选择数据库
use mysql
3.开启远程链接:

# mysql安装后默认是localhost访问，若是须要外部访问能够设置一个新的帐号把host改成%，意味着全部ip都可以访问
GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY '你的密码' WITH GRANT OPTION;

因为密码策略问题报错:

ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

缘由: MySQL5.6.6版本以后增长了密码强度验证插件validate_password，相关参数设置的较为严格。
使用了该插件会检查设置的密码是否符合当前设置的强度规则，若不知足则拒绝设置。影响的语句和函数有：create user,grant,set password,password(),old password。

解决参考:

# 查看mysql全局参数配置
mysql> select @@validate_password_policy; 
+----------------------------+
| @@validate_password_policy |
+----------------------------+
| MEDIUM                     |
+----------------------------+
1 row in set (0.01 sec)

mysql> SHOW VARIABLES LIKE 'validate_password%';
+--------------------------------------+--------+
| Variable_name                        | Value  |
+--------------------------------------+--------+
| validate_password_check_user_name    | OFF    |
| validate_password_dictionary_file    |        |
| validate_password_length             | 8      |
| validate_password_mixed_case_count   | 1      |
| validate_password_number_count       | 1      |
| validate_password_policy             | MEDIUM |
| validate_password_special_char_count | 1      |
+--------------------------------------+--------+
7 rows in set (0.00 sec)
# 修改mysql参数配置
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.00 sec)

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%';
+--------------------------------------+-------+
| Variable_name                        | Value |
+--------------------------------------+-------+
| validate_password_check_user_name    | OFF   |
| validate_password_dictionary_file    |       |
| validate_password_length             | 3     |
| validate_password_mixed_case_count   | 0     |
| validate_password_number_count       | 3     |
| validate_password_policy             | LOW   |
| validate_password_special_char_count | 0     |
+--------------------------------------+-------+
7 rows in set (0.01 sec)
# 配置完便可修改简单密码
mysql> set password for 'root'@'localhost' = password('简单密码');
Query OK, 0 rows affected, 1 warning (0.00 sec)

4.从新配置并重启服务

# 此时配置远程链接无报错
mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY '简单密码' WITH GRANT OPTIONN;
Query OK, 0 rows affected, 1 warning (0.00 sec)
# 刷新权限
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql> ^DBye
# 重启mysql服务
systemctl restart mysqld.service

ok, 能够远程链接了