Schedule recurring tasks using the system cron daemon.
medium risk
Cron runs scheduled commands based on a time expression (minute hour day month weekday). System cron jobs live in /etc/cron.d/, /etc/cron.daily/, etc. User cron jobs are managed via crontab. Each field: minute(0-59) hour(0-23) day(1-31) month(1-12) weekday(0-7).
crontab -eEdit current user's crontab · explain & risk-check →crontab -lList current user's cron jobs · explain & risk-check →crontab -l -u nginxList cron jobs for specific user · explain & risk-check →echo '0 2 * * * /opt/scripts/backup.sh >> /var/log/backup.log 2>&1' | crontab -Add a daily 2AM backup job · explain & risk-check →ls /etc/cron.d/ && cat /etc/cron.d/sysstatView system cron jobs · explain & risk-check →Always redirect cron output: `command >> /var/log/myjob.log 2>&1`. Without redirection, errors go to the user's mail (often ignored). Also set MAILTO='' in crontab to suppress email if not needed.
Reference text is hand-written and may be incomplete — check man cron for your version. Test destructive commands on a non-production system first.