[root@mserver0002 img]# cat /etc/my.cnf
[mysqld]
####basic settings####
#skip-grant-tables
default-storage-engine=INNODB
......

# 修改完配置文件后可以使用空密码登录（在Enter password:出现后直接敲enter键）
[root@ecs-ce5a-0001 etc]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
......

mysql> use mysql

Database changed
mysql> SET PASSWORD = PASSWORD('Smart@123');
ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'Smart@123';
ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement
mysql> update mysql.user set password=password('Smart@123') where user= 'root';
ERROR 1054 (42S22): Unknown column 'password' in 'field list'
mysql> desc mysql.user
    -> ;
+------------------------+-----------------------------------+------+-----+-----------------------+-------+
| Field                  | Type                              | Null | Key | Default               | Extra |
+------------------------+-----------------------------------+------+-----+-----------------------+-------+
| Host                   | char(60)                          | NO   | PRI |                       |       |
......
| authentication_string  | text                              | YES  |     | NULL                  |       |
| password_expired       | enum('N','Y')                     | NO   |     | N                     |       |
| password_last_changed  | timestamp                         | YES  |     | NULL                  |       |
| password_lifetime      | smallint(5) unsigned              | YES  |     | NULL                  |       |
| account_locked         | enum('N','Y')                     | NO   |     | N                     |       |
+------------------------+-----------------------------------+------+-----+-----------------------+-------+
45 rows in set (0.00 sec)

mysql> update mysql.user set authentication_string=password('Smart@123') 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 (0.01 sec)

mysql> exit
Bye
[root@ecs-ce5a-0001 etc]# mysql -uroot -p
# 在这里输入新设置的密码Smart@123
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
......

mysql> 

关于赋权的说明

??首先说说改密码，其实有下面两种途径都可以；而赋权则会涉及的比较多，可以参考下面的操作样例（关于用户权限管理，这么小小的一段是说不清楚的，后面会单独开新的章节进行详细说明）：

ALTER USER 'root'@'localhost' IDENTIFIED BY 'Smart@123';
flush privileges;

SET PASSWORD = PASSWORD('Smart@123');
ALTER USER 'root'@'localhost' PASSWORD EXPIRE NEVER;
flush privileges;

-- root全部赋权
grant all privileges on *.* to root@"%" identified by "Smart@123";
flush privileges;

-- 普通用户部分赋权
grant select,insert,update,delete on db_test.* to test@"%" identified by "Smart@2018";
flush privileges;

# 方法1
[root@ecs-ce5a-0001 ~]# mysql -V
mysql  Ver 14.14 Distrib 5.7.24, for Linux (x86_64) using  EditLine wrapper

# 方法2
[root@ecs-ce5a-0001 ~]# mysql --help |grep Distrib
mysql  Ver 14.14 Distrib 5.7.24, for Linux (x86_64) using  EditLine wrapper

# 方法3
[root@ecs-ce5a-0001 ~]# mysql -uroot -pKoncendy@123
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 12
Server version: 5.7.24-log 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>  select version();
+------------+
| version()  |
+------------+
| 5.7.24-log |
+------------+
1 row in set (0.00 sec)

# 方法4
mysql> status
--------------
mysql  Ver 14.14 Distrib 5.7.24, for Linux (x86_64) using  EditLine wrapper

Connection id:		12
Current database:	
Current user:		root@
SSL:			Not in use
Current pager:		stdout
Using outfile:		''
Using delimiter:	;
Server version:		5.7.24-log MySQL Community Server (GPL)
Protocol version:	10
Connection:		Localhost via UNIX socket
Server characterset:	utf8
Db     characterset:	utf8
Client characterset:	utf8
Conn.  characterset:	utf8
UNIX socket:		/data/mysql/mysql.sock
Uptime:			5 min 21 sec

Threads: 6  Questions: 293  Slow queries: 6  Opens: 195  Flush tables: 1  Open tables: 156  Queries per second avg: 0.912
--------------

mysql> 

---------------------------
mysqld.exe - 系统错误
---------------------------
无法启动此程序，因为计算机中丢失 MSVCP140.dll。尝试重新安装该程序以解决此问题。 
---------------------------
确定   
---------------------------

# Login
mysqladmin -u root -p 
......

# Execute SQL
ALTER USER 'root'@'localhost' IDENTIFIED BY 'password' PASSWORD EXPIRE NEVER;
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'admin123';
FLUSH PRIVILEGES;