mysqladmin -u root password NEW_PASSWORD                   # when root has no password
mysqladmin -u root -p OLD_PASSWORD password NEW_PASSWORD   # when root has password
mysqladmin -u user -p OLD_PASSWORD password NEW_PASSWORD

mysql> grant all on database_name.* to !username@localhost identified by "password"

mysqldump -u username -p database_name > /path/to/save/database_name.sql
mysqldump -u username -p --routines database_name > /path/to/save/database_name.sql
mysqldump -u username -p --alldatabases > /path/to/save/all_databases.sql

mysql -u username --protocol TCP -p database_name < /path/to/file/database.sql