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摘要：丢失root密码，意味着不能以超级管理员帐号登录数据库，进行维护工作。需要找回root密码。
概述
丢失root密码，意味着不能以超级管理员帐号登录数据库，进行维护工作。需要找回root密码。
处理方法
杀掉mysql进程，然后添加一个参数–skip-grant-tables跳过权限表，启动mysql实例，然后以无密码方式登录数据库，修改root用户密码，再关闭mysql实例（关闭或者kill mysql进程），最后正常启动mysql实例，就可以使用root用户登录数据库了。
关键操作代码
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mysql -uroot -p
ps -ef|grep mysql
kill -9 mysql进程号
mysqld_safe --defaults-file=/etc/my.cnf --skip-grant-tables &
mysql
use mysql；
update user set authentication_string=password(‘oracle123’) where user=‘root’;
flush privileges;
mysqladmin -p shutdown
mysqld_safe --defaults-file=/etc/my.cnf &
mysql -uroot -p
操作演示日志
[root@source ~]# mysql -uroot -p
Enter password:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES) ==故意输错密码，模拟root密码丢失==
[root@source ~]#
[root@source ~]# ps -ef|grep mysql
root 6733 6191 0 10:28 pts/0 00:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --defaults-file=/etc/my.cnf
mysql 7029 6733 2 11:10 pts/0 00:00:00 /usr/local/mysql/bin/mysqld --defaults-file=/etc/my.cnf --basedir=/usr/local/mysql --datadir=/data/mysql --plugin-dir=/usr/local/mysql/lib/plugin
--user=mysql --log-error=source.err --pid-file=source.pid --port=3306
root 7063 6191 0 11:10 pts/0 00:00:00 grep mysql
[root@source ~]#
[root@source ~]# kill -9 7029 6733
[root@source ~]#
[1]+ Killed mysqld_safe --defaults-file=/etc/my.cnf
[root@source ~]#
[root@source ~]# ps -ef|grep mysql
root 7066 6191 0 11:10 pts/0 00:00:00 grep mysql
[root@source ~]#
[root@source ~]#
[root@source ~]# mysqld_safe --defaults-file=/etc/my.cnf --skip-grant-tables &
[1] 7286
[root@source ~]# 2020-02-16T03:11:41.998645Z mysqld_safe Logging to '/data/mysql/source.err'.
2020-02-16T03:11:42.020962Z mysqld_safe Starting mysqld daemon with databases from /data/mysql
[root@source ~]#
[root@source ~]# mysql
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 3
Server version: 5.7.20-log MySQL Community Server (GPL)
Copyright (c) 2000, 2017, 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@db 11:11: [(none)]>
root@db 11:11: [(none)]>
root@db 11:12: [(none)]>
root@db 11:12: [(none)]> use mysql;
Database changed
root@db 11:12: [mysql]>
root@db 11:12: [mysql]> update user set authentication_string=password('oracle123') where user='root'; ==修改密码==
Query OK, 1 row affected, 1 warning (0.01 sec)
Rows matched: 2 Changed: 1 Warnings: 1
root@db 11:13: [mysql]>
root@db 11:13: [mysql]> flush privileges;
Query OK, 0 rows affected (0.00 sec)
root@db 11:13: [mysql]>
root@db 11:14: [mysql]> exit
Bye
[root@source ~]#
[root@source ~]# mysqladmin -p shutdown
Enter password:
[root@source ~]#
[root@source ~]# 2020-02-16T03:15:27.217666Z mysqld_safe mysqld from pid file /data/mysql/source.pid ended
[1]+ Done mysqld_safe --defaults-file=/etc/my.cnf --skip-grant-tables
[root@source ~]#
[root@source ~]# ps -ef|grep mysql
root 7502 6191 0 11:15 pts/0 00:00:00 grep mysql
[root@source ~]#
[root@source ~]# mysqld_safe --defaults-file=/etc/my.cnf &
[1] 7503
[root@source ~]# 2020-02-16T03:15:57.181920Z mysqld_safe Logging to '/data/mysql/source.err'.
2020-02-16T03:15:57.217614Z mysqld_safe Starting mysqld daemon with databases from /data/mysql
[root@source ~]#
[root@source ~]# mysql -uroot -p
Enter password: ==root密码找回后，正常登录==
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 4
Server version: 5.7.20-log MySQL Community Server (GPL)
Copyright (c) 2000, 2017, 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@db 11:16: [(none)]>