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B.1.4.1. How to Reset the Root Password

If you have never set a root password for MySQL, the server does not require a password at all for connecting as root. However, it is recommended to set a password for each account. See 項4.6.1. 「セキュリティ ガイドライン」.

If you set a root password previously, but have forgotten what it was, you can set a new password. The following procedure is for Windows systems. The procedure for Unix systems is given later in this section.

The procedure under Windows:

  1. Log on to your system as Administrator.

  2. Stop the MySQL server if it is running. For a server that is running as a Windows service, go to the Services manager: 

    Start Menu -> Control Panel -> Administrative Tools -> Services

    Then find the MySQL service in the list, and stop it.

    If your server is not running as a service, you may need to use the Task Manager to force it to stop.

  3. Create a text file and place the following command within it on a single line: 

    SET PASSWORD FOR 'root'@'localhost' = PASSWORD('MyNewPassword');

    Save the file with any name. For this example the file will be C:\mysql-init.txt.

  4. Open a console window to get to the DOS command prompt: 

    Start Menu -> Run -> cmd

  5. We are assuming that you installed MySQL to C:\mysql. If you installed MySQL to another location, adjust the following commands accordingly.

    At the DOS command prompt, execute this command: 

    C:\> C:\mysql\bin\mysqld-nt --init-file=C:\mysql-init.txt

    The contents of the file named by the --init-file option are executed at server startup, changing the root password. After the server has started successfully, you should delete C:\mysql-init.txt.

    If you install MySQL using the MySQL Installation Wizard, you may need to specify a --defaults-file option: 

    C:\> "C:\Program Files\MySQL\MySQL Server 5.1\bin\mysqld-nt.exe"
         --defaults-file="C:\Program Files\MySQL\MySQL Server 5.1\my.ini"
         --init-file=C:\mysql-init.txt

    The appropriate --defaults-file setting can be found using the Services Manager: 

    Start Menu -> Control Panel -> Administrative Tools -> Services

    Find the MySQL service in the list, right-click on it, and choose the Properties option. The Path to executable field contains the --defaults-file setting.

  6. Stop the MySQL server, then restart it in normal mode again. If you run the server as a service, start it from the Windows Services window. If you start the server manually, use whatever command you normally use.

  7. You should be able to connect using the new password.

In a Unix environment, the procedure for resetting the root password is as follows:

  1. Log on to your system as either the Unix root user or as the same user that the mysqld server runs as.

  2. Locate the .pid file that contains the server's process ID. The exact location and name of this file depend on your distribution, hostname, and configuration. Common locations are /var/lib/mysql/, /var/run/mysqld/, and /usr/local/mysql/data/. Generally, the filename has the extension of .pid and begins with either mysqld or your system's hostname.

    You can stop the MySQL server by sending a normal kill (not kill -9) to the mysqld process, using the pathname of the .pid file in the following command: 

    shell> kill `cat /mysql-data-directory/host_name.pid`

    Note the use of backticks rather than forward quotes with the cat command; these cause the output of cat to be substituted into the kill command.

  3. Create a text file and place the following command within it on a single line: 

    SET PASSWORD FOR 'root'@'localhost' = PASSWORD('MyNewPassword');

    Save the file with any name. For this example the file will be ~/mysql-init.

  4. Restart the MySQL server with the special --init-file=~/mysql-init option: 

    shell> mysqld_safe --init-file=~/mysql-init &

    The contents of the init-file are executed at server startup, changing the root password. After the server has started successfully you should delete ~/mysql-init.

  5. You should be able to connect using the new password.

Alternatively, on any platform, you can set the new password using the mysql client(but this approach is less secure):

  1. Stop mysqld and restart it with the --skip-grant-tables --user=root options (Windows users omit the --user=root portion).

  2. Connect to the mysqld server with this command: 

    shell> mysql -u root

  3. Issue the following statements in the mysql client: 

    mysql> UPDATE mysql.user SET Password=PASSWORD('newpwd')
    ->                   WHERE User='root';
mysql> FLUSH PRIVILEGES;

    Replace 「newpwd」 with the actual root password that you want to use.

  4. You should be able to connect using the new password.