回应rogerdpack的评论:如果你不知道MySQL的根密码，并且你不关心MySQL的数据/设置，你可以重新安装它并重置根密码，如下所示:

sudo apt-get remove --purge mysql-server mysql-client mysql-common
sudo rm -rf /var/lib/mysql
sudo apt-get install -y mysql-server mysql-client 

安装过程中，您可以选择root用户的密码:

修改MySQL root密码。

此方法将密码暴露到命令行历史记录中，这些命令应该以root身份运行。

通过mysql命令行工具登录: Mysql -uroot -poldpassword 执行如下命令: SET PASSWORD FOR root@ localhost = PASSWORD('newpassword');

or

运行此命令，为当前用户设置密码(在本例中为'root'): SET PASSWORD = PASSWORD('newpassword');

当你在你想要更改密码的系统上使用MySQL的PASSWORD()时，它可能会导致密码在MySQL日志中以cleartext [source]显示。对我来说，让它们和备份等像密码一样安全听起来像是噩梦，所以我喜欢这样做:

On your local machine, run this with your password: mysql -u someuser -p < <(echo "SELECT PASSWORD('mypass');") Note the space in front to prevent it from turning up in the bash history (for other distros than Ubuntu, this might work differently – source). On your server machine, execute the following command to change its MySQL root password (replace myhash with your password's hash as printed by the first command): mysql -u root -p < <(echo "SET PASSWORD FOR root@localhost = 'myhash';") Optionally, let's be a bit paranoid: On your local machine, clear your terminal screen with clear and purge your virtual terminal scrollback, to hide the cleartext password appearing in the command above.

关于这个话题的大多数答案都过时了;在写这个答案之前，MySQL发生了两个主要的变化:

1-用户表中的“Password”字段已被“authentication_string”列取代。

2-“Password”加密功能:Password(“of some text”)已弃用。

更多信息请参考此链接:dev.mysql.com/doc/refman/8.0/en/resetting-permissions.html

I had to go this route on Ubuntu 16.04.1 LTS. It is somewhat of a mix of some of the other answers above - but none of them helped. I spent an hour or more trying all other suggestions from MySql website to everything on SO, I finally got it working with: Note: while it showed Enter password for user root, I didnt have the original password so I just entered the same password to be used as the new password. Note: there was no /var/log/mysqld.log only /var/log/mysql/error.log Also note this did not work for me: sudo dpkg-reconfigure mysql-server-5.7 Nor did: sudo dpkg-reconfigure --force mysql-server-5.5 Make MySQL service directory. sudo mkdir /var/run/mysqld Give MySQL user permission to write to the service directory. sudo chown mysql: /var/run/mysqld Then:

kill the current mysqld pid run mysqld with sudo /usr/sbin/mysqld & run /usr/bin/mysql_secure_installation Output from mysql_secure_installation root@myServer:~# /usr/bin/mysql_secure_installation Securing the MySQL server deployment. Enter password for user root: VALIDATE PASSWORD PLUGIN can be used to test passwords and improve security. It checks the strength of password and allows the users to set only those passwords which are secure enough. Would you like to setup VALIDATE PASSWORD plugin? Press y|Y for Yes, any other key for No: no Using existing password for root. Change the password for root ? ((Press y|Y for Yes, any other key for No) : y New password: Re-enter new password: By default, a MySQL installation has an anonymous user, allowing anyone to log into MySQL without having to have a user account created for them. This is intended only for testing, and to make the installation go a bit smoother. You should remove them before moving into a production environment. Remove anonymous users? (Press y|Y for Yes, any other key for No) : y Success. Normally, root should only be allowed to connect from 'localhost'. This ensures that someone cannot guess at the root password from the network. Disallow root login remotely? (Press y|Y for Yes, any other key for No) : y Success. By default, MySQL comes with a database named 'test' that anyone can access. This is also intended only for testing, and should be removed before moving into a production environment. Remove test database and access to it? (Press y|Y for Yes, any other key for No) : y Dropping test database... Success. Removing privileges on test database... Success. Reloading the privilege tables will ensure that all changes made so far will take effect immediately. Reload privilege tables now? (Press y|Y for Yes, any other key for No) : y Success. All done!

重置或修改密码请输入sudo dpkg-reconfigure mysql-server-X。X (X.X是mysql版本你已经安装，即5.6,5.7)，然后你会提示一个屏幕，你必须设置新密码，然后在下一步确认密码，只是等待一会儿。就是这样。