apt install mysql-server, 莫名其妙的就装完了，都没有让我设置密码，现在只能通过其他方式来重置密码。
# Stop MySQL
sudo service mysql stop
# 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
# Start MySQL manually, without permission checks or networking.
sudo mysqld_safe --skip-grant-tables --skip-networking &
# Log in without a password.
mysql -uroot mysql然后就可以通过 SQL 修改 root 密码了
UPDATE mysql.user SET authentication_string=PASSWORD('root'), plugin='mysql_native_password' WHERE User='root' AND Host='%';
UPDATE mysql.user SET authentication_string=PASSWORD('root'), plugin='mysql_native_password' WHERE User='root' AND Host='localhost';
EXIT;# Turn off MySQL.
sudo mysqladmin -S /var/run/mysqld/mysqld.sock shutdown
# Start the MySQL service normally.
sudo service mysql start