The syntax of the crontab is extremely sensitive - additional spaces or lines will cause a cron job to fail. Avoid using graphical editors to modify the crontab, as they can insert special characters - Your safest bet is to use vi
- Set the default editor
- Issue the following to edit the crontab:
- Save the crontab using :wq
# EDITOR=vi # export EDITOR
# crontab -e
#ident "@(#)root 1.19 98/07/06 SMI" /* SVr4.0 1.1.3.1 */ # # The root crontab should be used to perform accounting data collection. # # The rtc command is run to adjust the real time clock if and when # daylight savings time changes. # 10 3 * * 0,4 /etc/cron.d/logchecker 10 3 * * 0 /usr/lib/newsyslog 15 3 * * 0 /usr/lib/fs/nfs/nfsfind 1 2 * * * [ -x /usr/sbin/rtc ] && /usr/sbin/rtc -c > /dev/null 2>&1 30 3 * * * [ -x /usr/lib/gss/gsscred_clean ] && /usr/lib/gss/gsscred_clean 25 0,12 * * * /usr/bin/cat /dev/null > /var/log/privoxy/logfile
In the example above, I added a cronjob to cat /dev/null to the /var/log/privoxy/logfile at 25 minutes past midnight and 25 minutes past noon every day. Let's break it down:
25 0,12 * * * /usr/bin/cat /dev/null > /var/log/privoxy/logfile - - - - - | | | | | | | | | +---- day of week (0 - 6) (Sunday=0) | | | +---------- month (1 - 12) | | +---------------- day of month (1 - 31) | +---------------------- hour (0 - 23) +---------------------------- min (0 - 59)