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:

你不需要这些。只需登录:

Mysql -u root -p

然后按照mysql>提示修改当前用户的密码:

mysql> set password=password('the_new_password');
mysql> flush privileges;

正如mysql文档中password()函数所说:

此函数在MySQL 8.0.11中被移除。

这将使mysql v8.0.11及更新版本的所有现有答案都失效。

根据mysql文档，重置root密码的新通用方法如下:

The preceding sections provide password-resetting instructions specifically for Windows and Unix and Unix-like systems. Alternatively, on any platform, you can reset the password using the mysql client (but this approach is less secure): Stop the MySQL server if necessary, then restart it with the --skip-grant-tables option. This enables anyone to connect without a password and with all privileges, and disables account-management statements such as ALTER USER and SET PASSWORD. Because this is insecure, if the server is started with the --skip-grant-tables option, it enables --skip-networking automatically to prevent remote connections. Connect to the MySQL server using the mysql client; no password is necessary because the server was started with --skip-grant-tables: shell> mysql In the mysql client, tell the server to reload the grant tables so that account-management statements work: mysql> FLUSH PRIVILEGES; Then change the 'root'@'localhost' account password. Replace the password with the password that you want to use. To change the password for a root account with a different host name part, modify the instructions to use that host name. mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass'; You should now be able to connect to the MySQL server as root using the new password. Stop the server and restart it normally (without the --skip-grant-tables and --skip-networking options).

要更新“root”Mysql用户密码，你必须记住，你将需要超级用户权限。如果您拥有超级用户权限，请尝试执行以下命令:

MySQL 5.7.6及以上版本

sudo su
service mysql stop
mysql -u root
ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass';
\q;
exit
mysql -u root -p MyNewPass

MySQL 5.7.5及更早版本

sudo su
service mysql stop
mysql -u root
SET PASSWORD FOR 'root'@'localhost' = PASSWORD('MyNewPass');
\q;
exit
mysql -u root -p MyNewPass

这就像我为Ubuntu 16.04做的一样。 完全归功于下面的链接，因为我从那里得到了它。 [https://coderwall.com/p/j9btlg/reset-the-mysql-5-7-root-password-in-ubuntu-16-04-lts] [1]

停止MySQL

sudo service mysql stop

制作MySQL服务目录。 Sudo mkdir /var/run/mysqld

赋予MySQL用户写入服务目录的权限。

sudo chown mysql: /var/run/mysqld

手动启动MySQL，不需要权限检查或联网。

sudo mysqld_safe --skip-grant-tables --skip-networking &

无需密码即可登录。

mysql -uroot mysql

更新root用户密码。 确保下面的查询至少更新了根帐户。 如果您愿意，进行一些选择并检查现有的值

UPDATE mysql.user SET 
authentication_string=PASSWORD('YOURNEWPASSWORD'), 
plugin='mysql_native_password' WHERE User='root';
EXIT;

关闭MySQL。

sudo mysqladmin -S /var/run/mysqld/mysqld.sock shutdown

正常启动MySQL服务。

sudo service mysql start

1.打开nano / vim，创建一个包含以下内容的文件，并将文件保存为~/mysql-pwd

ALTER USER 'root'@'localhost' IDENTIFIED BY 'NEWPASSWORD';

停止mysql sudo systemctl停止mysql 执行sudo mysqld -init-file=~/mysql-pwd命令 重启mysql sudo systemctl start mysql 现在登录mysql -u root -p。password将是你的NEWPASSWORD