Mariadb changes the root password

By default, the password of the newly installed mariadb is empty. You can log in to the database by directly entering mysql in the shell terminal.

If it is the first time you have just installed it, use the MySQL? Secure? Installation command to initialize it.

# mysql_secure_installation

NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB
      SERVERS IN PRODUCTION USE!  PLEASE READ EACH STEP CAREFULLY!

In order to log into MariaDB to secure it, we'll need the current
password for the root user.  If you've just installed MariaDB, and
you haven't set the root password yet, the password will be blank,
so you should just press enter here.

Enter current password for root (enter for none):
OK, successfully used password, moving on...

Setting the root password ensures that nobody can log into the MariaDB
root user without the proper authorisation.

Set root password? [Y/n] y
New password:
Re-enter new password:
Password updated successfully!
Reloading privilege tables..
 ... Success!


By default, a MariaDB installation has an anonymous user, allowing anyone
to log into MariaDB without having to have a user account created for
them.  This is intended only for testing, and to make the installation
go a bit smoother.  You should remove them before moving into a
production environment.

Remove anonymous users? [Y/n] y
 ... Success!

Normally, root should only be allowed to connect from 'localhost'.  This
ensures that someone cannot guess at the root password from the network.

Disallow root login remotely? [Y/n] y
 ... Success!

By default, MariaDB comes with a database named 'test' that anyone can
access.  This is also intended only for testing, and should be removed
before moving into a production environment.

Remove test database and access to it? [Y/n] y
 - Dropping test database...
 ... Success!
 - Removing privileges on test database...
 ... Success!

Reloading the privilege tables will ensure that all changes made so far
will take effect immediately.

Reload privilege tables now? [Y/n] y
 ... Success!

Cleaning up...

All done!  If you've completed all of the above steps, your MariaDB
installation should now be secure.

Thanks for using MariaDB!

This is for the situation that the root password is known and needs to be modified.

There are two modification methods:

1. Modify directly from the shell command line using the mysqladm command.

# mysqladmin -uroot -poldpassword password newpassword

The disadvantage of this method is that the password will be displayed in clear text.

2. Log in to the database to change the password.

# mysql -uroot -p

2.1 To update mysql In Library user Fields of the table:
MariaDB [(none)]> use mysql;  
MariaDB [mysql]> UPDATE user SET password=password('newpassword') WHERE user='root';  
MariaDB [mysql]> flush privileges;  
MariaDB [mysql]> exit;

2.2 Or, use set Instruction set root Password:
MariaDB [(none)]> SET password for 'root'@'localhost'=password('newpassword');  
MariaDB [(none)]> exit; 

If you forget the root password, you need to start mariadb to change the password by skipping authorization.

1. Stop the service first.

# systemctl stop mariadb

2. Start mariadb by skipping authorization.

# mysqld_safe --skip-grant-tables &
[1] 1441
[root@centos7 ~]# 170531 02:10:28 mysqld_safe Logging to '/var/log/mariadb/mariadb.log'.
170531 02:10:28 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql

# ps -ef | grep 1441
root      1441   966  0 02:10 pts/0    00:00:00 /bin/sh /usr/bin/mysqld_safe --skip-grant-tables
mysql     1584  1441  0 02:10 pts/0    00:00:00 /usr/libexec/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --user=mysql --skip-grant-tables --log-error=/var/log/mariadb/mariadb.log --pid-file=/var/run/mariadb/mariadb.pid --socket=/var/lib/mysql/mysql.sock

3. When skipping the authorization startup, you can log in to the database directly without password. Login to update password.

# mysql
MariaDB [(none)]> use mysql;  
MariaDB [mysql]> UPDATE user SET password=password('newpassword') WHERE user='root';  
MariaDB [mysql]> flush privileges;   
MariaDB [mysql]> exit; 

After the password is updated, you can't log in directly without the password when you skip the authorization startup.

4. To close a process that skipped authorization start:

# kill -9 1441 

5. Start mariadb normally:

# systemctl start mariadb