MySQL

References

• http://www.cyberciti.biz/faq/mysql-change-root-password/
• http://www.cyberciti.biz/tips/recover-mysql-root-password.html

Passwords

Use option file for password

Instead of giving password on the command-line with option -p PWD, a safer method is to use a password file:

• Create a file ~/.my.cnf:

[mysl]
user=root
password="PASSWORD"

This file must contain an entry for all tools used. For instance:

[client]
user=root
password="PASSWORD"

[mysql]
user=root
password="PASSWORD"

[mysqldump]
user=root
password="PASSWORD"

[mysqldiff]
user=root
password="PASSWORD"

• Change file permission:

 chmod 600 ~/.my.cnf

• Now we can connect without exposing the password:

 mysql -u root

Change

Using mysqladmin:

unset HISTFILE                                       # <-- DO NOT FORGET IT, OR PWD WILL APPEAR IN ~/.bash_history
mysqladmin -u USERNAME password NEWPWD               # Assumes no password set - use user=root for admin pwd
mysqladmin -u USERNAME -p'OLDPWD' password NEWPWD

If you forget to unset HISTFILE, delete your history file immediately:

rm ~/.bash_history

Using MySQL commands. First we connect to MySQL server and select table mysql (don't forget to DISABLE HISTORY FILE !!!):

MYSQL_HISTFILE=/dev/null mysql -u root -p mysql

Here the script:

update user set password=PASSWORD("NEWPWD") where User='USERNAME';
flush privileges;
quit

Recover root password

If the MySQL root password is lost, the same script can be used to define a new password, but it requires to restart the MySQL server with option --skip-grant-tables:

sudo service mysql stop                       # Stop MySQL server
sudo mysqld_safe --skip-grant-tables &        # Restart it with option not to ask for passwords
sudo su
MYSQL_HISTFILE=/dev/null mysql -u root mysql  # Connect to MySQL, table mysql

Apply the MySQL script above:

update user set password=PASSWORD("NEWPWD") where User='root';
flush privileges;
quit

Then restart the server:

sudo /etc/init.d/mysql stop
sudo service mysql start

Backup / Restore

To backup / restore all mysql database over the network [1]:

unset HISTFILE                         # Or use option file to avoid exposing the password
mysqldump -u root -pPASSWORD --all-databases | ssh USER@NEW.HOST.COM 'cat - | mysql -u root -pPASSWORD'