What is the default root pasword for MySQL 5.7

MySQL 5.7 changed the secure model: now MySQL root login requires a sudo

The simplest (and safest) solution will be create a new user and grant required privileges.

1. Connect to mysql

sudo mysql --user=root mysql

2. Create a user for phpMyAdmin

CREATE USER 'phpmyadmin'@'localhost' IDENTIFIED BY 'some_pass';
GRANT ALL PRIVILEGES ON *.* TO 'phpmyadmin'@'localhost' WITH GRANT OPTION;
FLUSH PRIVILEGES;

Reference - https://askubuntu.com/questions/763336/cannot-enter-phpmyadmin-as-root-mysql-5-7

MySQL server 5.7 was already installed by default on my new Linux Mint 19.

But, what's the MySQL root password? It turns out that:

The default installation uses auth_socket for authentication, in lieu of passwords!

It allows a password-free login, provided that one is logged into the Linux system with the same user name. To login as the MySQL root user, one can use sudo:

sudo mysql --user=root

But how to then change the root password? To illustrate what's going on, I created a new user "me", with full privileges, with:

mysql> CREATE USER 'me'@'localhost' IDENTIFIED BY 'my_new_password';
mysql> GRANT ALL PRIVILEGES ON *.* TO 'me'@'localhost' WITH GRANT OPTION;
mysql> FLUSH PRIVILEGES;

Comparing "me" with "root":

mysql> SELECT user, plugin, HEX(authentication_string)  FROM mysql.user WHERE user = 'me' or user = 'root';
+------+-----------------------+----------------------------------------------------------------------------+
| user | plugin                | HEX(authentication_string)                                                 |
+------+-----------------------+----------------------------------------------------------------------------+
| root | auth_socket           |                                                                            |
| me   | mysql_native_password | 2A393846353030304545453239394634323734333139354241344642413245373537313... |
+------+-----------------------+----------------------------------------------------------------------------+

Because it's using auth_socket, the root password cannot be changed: the SET PASSWORD command fails, and mysql_secure_installation desn't attain anything...

==> To zap this alternate authentication mode and return the MySQL root user to using passwords:

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'SOME_NEW_ROOT_PASSWORD';

A good explanation.

More details from the MySQL manual.

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!

After you installed MySQL-community-server 5.7 from fresh on linux, you will need to find the temporary password from /var/log/mysqld.log to login as root.

1. grep 'temporary password' /var/log/mysqld.log
2. Run mysql_secure_installation to change new password

ref: http://dev.mysql.com/doc/refman/5.7/en/linux-installation-yum-repo.html