1.修改配置文件

vi /etc/my.cnf

在[mysqld]的段中加上一句

  skip-grant-tables

2.保存重启 mysql

 service mysqld restart

3.修改root密码

[root@jason bin]# 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('jason_zhang') where user='root';
Query OK, 0 rows affected, 1 warning (0.00 sec)
Rows matched: 2  Changed: 0  Warnings: 1
mysql> flush privileges;
mysql> quit


或者

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

4.删除配置文件中的 skip-grant-tables

 步骤1 中，在配置文件中新增的部分，删除；

5.保存重启 mysql

 service mysqld restart

6.登录 mysql,设置登录权限

mysql -u root -p

Enter password:
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 5
Server version: 5.7.15 MySQL Community Server (GPL)

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> GRANT ALL PRIVILEGES ON  *.* TO 'root'@'%' IDENTIFIED BY 'your root password' WITH GRANT OPTION;
Query OK, 0 rows affected, 1 warning (0.00 sec)

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



参考： http://blog.51cto.com/liuqh/2061241