cron_setting

# check cron status
(centos)
/etc/init.d/crond status

(ubuntu)
/etc/init.d/cron status
sudo service cron status

# edit own cron setting
crontab -e

# stop send mail to announce
MAILTO=""

# where is a log file
/var/log/cron (centos)
/var/log/syslog (ubuntu)

# access control
# create file to allow and fill out that allowed user name
/etc/cron.allow

# create file to deny and fill out that denied user name
etc/cron.deny