If you have set a root password, but forgot what it was, you can set a new password with the following procedure:
1. Take down the mysqld server by sending a kill (not kill -9) to the mysqld server. The pid is stored in a `.pid' file, which is normally in the MySQL database directory:
shell> kill `cat /mysql-data-directory/hostname.pid`
You must be either the Unix root user or the same user mysqld runs as to do this.
2. Restart mysqld with the --skip-grant-tables option.
3. Set a new password with the mysqladmin password command:
shell> mysqladmin -u root password 'mynewpassword'
4. Now you can either stop mysqld and restart it normally, or just load the privilege tables with:
shell> mysqladmin -h hostname flush-privileges
5. After this, you should be able to connect using the new password.
Alternatively, you can set the new password using the mysql client:
1. Take down and restart mysqld with the --skip-grant-tables option as described above.
2. Connect to the mysqld server with:
shell> mysql -u root mysql
3. Issue the following commands in the mysql client:
mysql> UPDATE user SET Password=PASSWORD('mynewpassword')
-> WHERE User='root';
mysql> FLUSH PRIVILEGES;
4. After this, you should be able to connect using the new password.
5. You can now stop mysqld and restart it normally.