I wanted to switch on the query log of MySQL. So I added the following to /etc/my.cnf
[mysqld] log = /var/log/mysql.log
and restarted the server: sudo /etc/init.d/mysql restart, but no log file occured even if I executed some queries.
The Problem was that mysql had no rights for /var/log. So the solution was to create an own directory for mysql
cd /var/log sudo mkdir mysql sudo chown mysql:mysql mysql/
and log into it:
log = /var/log/mysql/mysql.log
