//查看mysql服务状态

[root@mytestlnx02 ~]# ps -ef | grep -i mysql

root     22972     1  0 14:18 pts/0    00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --socket=/var/lib/mysql/mysql.sock --pid-file=/var/run/mysqld/mysqld.pid --basedir=/usr --user=mysql

mysql    23166 22972  0 14:18 pts/0    00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysqld.log --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/lib/mysql/mysql.sock

root     23237 21825  0 14:22 pts/0    00:00:00 grep -i mysql

//关闭服务

[root@mytestlnx02 ~]# service mysql stop

[root@mytestlnx02 ~]#

[mysqld]

skip-grant-tables

[root@mytestlnx02 ~]# service mysqld start

[root@mytestlnx02 ~]#

[root@mytestlnx02 ~]# mysql -u root

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

mysql> use mysql;

Reading table information for completion of table and column names

You can turn off this feature to get a quicker startup with -A

Database changed

mysql> update mysql.user set authentication_string=password('root_password') where user='root';

Query OK, 1 row affected, 1 warning (0.00 sec)

Rows matched: 1  Changed: 1  Warnings: 1

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

mysql> exit

[root@mytestlnx02 ~]# service mysql start

[root@mytestlnx02 ~]#

[root@mytestlnx02 ~]# mysql -u root -p

Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.

mysql> update user set authentication_string=password('xxxxxxxx') where User='root';      

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '('root_password') where User='root'' at line 1

[root@VM_0_8_centos ~]# grep 'temporary password' /var/log/mysqld.log

2018-09-26T04:25:54.927944Z 5 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: DN34N/=?aIfZ

[root@VM_0_8_centos ~]# mysql -u root -p

Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 8

Server version: 8.0.12 MySQL Community Server - GPL

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

mysql> ALTER USER 'root' IDENTIFIED BY 'xxxxxxxxx'; 

ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'xxxxxxxx';

Query OK, 0 rows affected (0.11 sec)

mysql> flush privileges;

Query OK, 0 rows affected (0.01 sec)

mysql> exit

Bye

[root@VM_0_8_centos ~]# service mysqld stop

Redirecting to /bin/systemctl stop  mysqld.service

[root@VM_0_8_centos ~]# service mysqld start

Redirecting to /bin/systemctl start  mysqld.service