root@zw-test-db bin]# ./mysqld_safe --user=mysql &
[1] 12455 
[root@zw-test-db bin]# 160830 15:18:01 mysqld_safe Logging to '/usr/local/mysql/data/zw-test-db.err'. 
160830 15:18:01 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/data 

[root@zw-test-db bin]# /etc/init.d/mysqld restart
Shutting down MySQL..160830 15:18:14 mysqld_safe mysqld from pid file /usr/local/mysql/data/zw-test-db.pid ended
        [ OK ]
 
Starting MySQL.      [ OK ] 
[1]+ Done   ./mysqld_safe --user=mysql 

[root@zw-test-db bin]# service mysqld restart 
Shutting down MySQL..     [ OK ]
Starting MySQL.      [ OK ] 
[root@zw-test-db bin]# 

[root@zw-test-db mysql]# mysql -u root -p 
Enter password: 
Welcome to the MySQL monitor. Commands end with ; or \g. 
Your MySQL connection id is 3 
Server version: 5.7.14-log 


Copyright (c) 2000, 2016, 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. 

root@localhost [(none)]>show databases; --提示要修改密码 
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement. 

root@localhost [(none)]>alter user user() identified by '123456'; 
Query OK, 0 rows affected (0.00 sec) 

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

root@localhost [(none)]>show databases;
+--------------------+ 
| Database  | 
+--------------------+ 
| information_schema | 
| mysql  | 
| performance_schema | 
| sys  | 
+--------------------+ 
4 rows in set (0.00 sec) 

delete from mysql.user where user!='root' or host!='localhost'; --删除非root用户，登陆主机不是localhost的账号 
flush privileges; 
alter user user() identified by '123456'; 
drop database test; 
truncate mysql.db;