My SQL

To change the password of an existing user

 mysql -u root -p
 use mysql;
 UPDATE USER set password = password('password') 
 WHERE host = 'localhost' and user = 'username';
 FLUSH PRIVILEGES;

To change the mysql root password

 # mysqladmin -u root password <new_password>

To backup mysql database

 mysqldump -u[mysqluser] -p[mysqlpswd] -h[mysqlhost] [mysqlport] [mysqldb] > outputfile_name

To create and restore database 'vpopmail' from mysqldump file 'vpopmail'

 mysqladmin -uroot -p<passwd> flush-tables 
 mysqladmin create <dbname> -uroot -p<passwd>
 mysql -uroot -p<passwd> vpopmail < vpopmail
 mysqladmin -uroot -p<passwd> reload
 mysqladmin -uroot -p<passwd> refresh

Granding and permissions and creating new accounts

 mysql> GRANT ALL PRIVILEGES ON <dbname> TO 'username'@'localhost'
    ->     IDENTIFIED BY 'some_pass';  
 mysql> GRANT ALL PRIVILEGES ON *.* TO 'monty'@'localhost'
    ->     IDENTIFIED BY 'some_pass' WITH GRANT OPTION; 
 mysql> GRANT ALL PRIVILEGES ON *.* TO 'monty'@'%'
    ->     IDENTIFIED BY 'some_pass' WITH GRANT OPTION;
 mysql> GRANT RELOAD,PROCESS ON *.* TO 'admin'@'localhost';
 mysql> GRANT USAGE ON *.* TO 'dummy'@'localhost';


 echo "GRANT ALL PRIVILEGES ON vpopmail.* TO vpopmail@localhost IDENTIFIED 
 BY 'SsEeCcRrEeTt'" | mysql -uroot -p$MYSQLPW