我遇到ubuntu 18.04和mysql 5.7的问题，这是解决方案

执行命令前请尝试重新启动mysql-server

sudo service mysql restart

Mysql-server >= 5.7

sudo mysql -uroot -p
USE mysql;
UPDATE user SET authentication_string=PASSWORD('YOUR_PASSWORD') WHERE User='root';
UPDATE user SET plugin="mysql_native_password";
FLUSH PRIVILEGES;
quit;

Mysql-server < 5.7

sudo mysql -uroot -p
USE mysql;
UPDATE user SET password=PASSWORD('YOUR_PASSWORD') WHERE User='root';
UPDATE user SET plugin="mysql_native_password";
FLUSH PRIVILEGES;
quit;

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).

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。

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

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 &

5.无需密码登录。 Mysql -uroot Mysql

6.更新root用户密码。

更新mysql。user SET authentication_string=PASSWORD('YOURNEWPASSWORD')， plugin='mysql_native_password' WHERE user ='root' AND Host='%'; 退出;

关闭MySQL。 sudo mysqladmin -S /var/run/mysqld/mysqld.袜子关闭 正常启动MySQL服务。 Sudo服务mysql启动

对我有用的(Ubuntu 16.04, mysql 5.7):

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 &

在另一个控制台，无需密码登录。

mysql -uroot mysql

然后:

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

关闭MySQL。

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

正常启动MySQL服务。

sudo service mysql start