Восстановление пользователя debian-sys-maint
etc
/etc/mysql/debian.cnf
USE mysql; INSERT INTO `user` ( `Host`, `User`, `Password`, `Select_priv`, `Insert_priv`, `Update_priv`, `Delete_priv`, `Create_priv`, `Drop_priv`, `Reload_priv`, `Shutdown_priv`, `Process_priv`, `File_priv`, `Grant_priv`, `References_priv`, `Index_priv`, `Alter_priv`, `Show_db_priv`, `Super_priv`, `Create_tmp_table_priv`, `Lock_tables_priv`, `Execute_priv`, `Repl_slave_priv`, `Repl_client_priv`, `Create_view_priv`, `Show_view_priv`, `Create_routine_priv`, `Alter_routine_priv`, `Create_user_priv`, `ssl_type`, `ssl_cipher`, `x509_issuer`, `x509_subject`, `max_questions`, `max_updates`, `max_connections`, `max_user_connections`, `authentication_string` -- MariaDB ) VALUES ( 'localhost', 'debian-sys-maint', password('PASSWORD-HERE'), 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'N', 'N', 'N', 'N', 'N', '', '', '', '', 0, 0, 0, 0, '' );
UPDATE `user` SET `password`=PASSWORD('PASSWORD-HERE') WHERE `user`='debian-sys-maint'; FLUSH PRIVILEGES;
mysql -uroot -p mysql < restore-debian.sql