The /etc/my.cnf File Configuration

Most of the cases you should not touch this file. By default it will have following entries:
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
[mysql.server]
user=mysql
basedir=/var/lib
[safe_mysqld]
err-log=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
Here you can specify a different directory for error log, otherwise you should not change any entry in this table