What is the default root pasword for MySQL 5.7

There’s so many answers out there saying to reinstall mysql or use some combo of

mysqld_safe --skip-grant-tables

and / or

UPDATE mysql.user SET Password=PASSWORD('password')

and / or something else …

… None of it was working for me

Here’s what worked for me, on Ubuntu 18.04, from the top

With special credit to this answer for digging me out of the frustration on this …

$ sudo apt install mysql-server
$ sudo cat /etc/mysql/debian.cnf

Note the lines which read:

user     = debian-sys-maint
password = blahblahblah

Then:

$ mysql -u debian-sys-maint -p
Enter password: // type 'blahblahblah', ie. password from debian.cnf

mysql> USE mysql
mysql> SELECT User, Host, plugin FROM mysql.user;
+------------------+-----------+-----------------------+
| User             | Host      | plugin                |
+------------------+-----------+-----------------------+
| root             | localhost | auth_socket           |
| mysql.session    | localhost | mysql_native_password |
| mysql.sys        | localhost | mysql_native_password |
| debian-sys-maint | localhost | mysql_native_password |
+------------------+-----------+-----------------------+
4 rows in set (0.00 sec)

mysql> UPDATE user SET plugin='mysql_native_password' WHERE User="root";
mysql> COMMIT;  // When you don't have auto-commit switched on

Either:

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'new_password';

Or:

// For MySQL 5.7+
UPDATE mysql.user SET authentication_string=PASSWORD('new_password') where user="root";

Then:

mysql> FLUSH PRIVILEGES;
mysql> COMMIT;  // When you don't have auto-commit switched on
mysql> EXIT

$ sudo service mysql restart
$ mysql -u root -p
Enter password: // Yay! 'new_password' now works!