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!