编辑MysqL的配置文件/etc/MysqL/my.cnf，在[MysqLd]段下加入一行“skip-grant-tables”。

重启MysqL服务

yxj @yxj:~$ sudo service MysqL restart

用空密码进入MysqL管理命令行，切换到MysqL库。

yxj @yxj:~$ MysqL
Welcome to the MysqL monitor. Commands end with ; or \g.

MysqL> use MysqL
Database changed

执行update MysqL.user set authentication_string=password('123qwe') where user='root' and Host ='localhost';把密码重置为123456。退出数据库管理。

MysqL> update MysqL.user set authentication_string=password('123qwe') where user='root' and Host ='localhost';
Query OK,0 rows affected (0.00 sec)
Rows matched: 4 Changed: 0 Warnings: 0

MysqL>update user set plugin="MysqL_native_password";  MysqL>flush privileges; MysqL>quit; 

回到sudo gedit /etc/MysqL/MysqL.conf.d/MysqLd.cnf，把刚才加入的那一行“skip-grant-tables”注释或删除掉。

再次重启MysqL服务sudo service MysqL restart，使用新的密码登陆，修改成功。

yxj @yxj:~$ MysqL -uroot -pnew_pass
Welcome to the MysqL monitor. Commands end with ; or \g.
MysqL>

 MysqL>MysqL -u root -p 再次登录