how to enable mysql general logging using query without restarting server on ubuntu lucid 10.4.2

to see what's going on inside mysql without restarting server, logging can be enabled using following query

SET GLOBAL general_log_file = '/var/log/mysql/mysql.log';
SET GLOBAL general_log = 'ON'

and logging can be disabled using following query

SET GLOBAL general_log = 'OFF'