--skip-grant-tables　　　　:跳过授权表
--skip-networking　　　　  :跳过TCP/IP连接

[root@master1 ~]# pkill mysqld
[root@master1 ~]# /etc/init.d/mysqld start
Starting MySQL. SUCCESS! 
[root@master1 ~]# /etc/init.d/mysqld stop
Shutting down MySQL.. SUCCESS! 
[root@master1 ~]# systemctl start mysqld --skip-grant-tables
systemctl: unrecognized option ‘--skip-grant-tables‘
[root@master1 ~]# service mysqld start --skip-grant-tables
Starting MySQL. SUCCESS! 
[root@master1 ~]# mysql

[root@master1 ~]# systemctl stop mysqld

[root@master1 ~]# mysqld_safe --skip-grant-tables --skip-networking &
或者
[root@master1 ~]# service mysqld start --skip-grant-tables --skip-networking

[root@master1 ~]# mysql

mysql> alter user root@‘localhost‘ identified by ‘mysql‘;
ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement
mysql>
mysql> flush privileges;    # 手工加载授权表
mysql> alter user root@‘localhost‘ identified by ‘mysql‘;

[root@master1 ~]# service mysqld restart
Shutting down MySQL.. SUCCESS! 
Starting MySQL. SUCCESS!