crontab: schedule recurring jobs

Updated November 2026

The cron daemon runs commands on a schedule: every night, every Monday, every five minutes. Each user has a crontab, a table of jobs, edited with the crontab command.

crontab -e # edit your crontab crontab -l # list it crontab -r # remove it (careful: no confirmation) crontab -u user -e # as root: edit another user's crontab

The five time fields

# ┌───────── minute (0-59)
# │ ┌─────── hour (0-23)
# │ │ ┌───── day of month (1-31)
# │ │ │ ┌─── month (1-12)
# │ │ │ │ ┌─ day of week (0-7, 0 and 7 = Sunday)
# │ │ │ │ │
  * * * * *  command to run

Schedule	Meaning
`30 2 * * *`	Every day at 02:30
`/5 * * *`	Every 5 minutes
`0 * * * *`	Every hour, on the hour
`0 9 * * 1-5`	09:00 Monday to Friday
`0 0 1 * *`	Midnight on the first of every month
`15 3 * * 0`	03:15 every Sunday
`0 8,12,17 * * *`	08:00, 12:00 and 17:00
`@reboot`	Once at start-up
`@daily`, `@weekly`, `@monthly`	Shortcuts (Vixie cron, cronie)

If both day of month and day of week are set, the job runs when either matches. Times are in the system's time zone.

Example crontab

MAILTO=admin@example.com
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

# nightly database dump
30 2 * * * /usr/local/bin/db-backup.sh >> /var/log/db-backup.log 2>&1

# clean temporary uploads older than 7 days, every hour
0 * * * * find /srv/app/tmp -type f -mtime +7 -delete

# renew a report every weekday morning
0 7 * * 1-5 cd /opt/reports && ./build.sh --quiet

Why does my job work in the shell but not in cron?

PATH: cron runs with a minimal PATH (often just /usr/bin:/bin). Use full paths to programs, or set PATH at the top of the crontab.
Environment: your .bashrc and .profile are not read. Set the variables the job needs in the script.
Working directory: jobs start in the home directory. cd first or use absolute paths.
The % sign has a special meaning in crontab lines (newline). Escape it: date +\%F.
Output: output is e-mailed to the user if mail is set up, otherwise lost. Redirect it to a log file with >> file 2>&1 while debugging.
Shell: cron uses /bin/sh; bash features fail unless you call a bash script or set SHELL=/bin/bash.

Check whether cron ran the job in the logs: journalctl -u cron (Debian, Ubuntu; -u crond on RHEL), or grep CRON /var/log/syslog where rsyslog is installed.

System cron

/etc/crontab and files in /etc/cron.d/ have an extra field, the user to run as: 30 2 * * * root /usr/local/bin/backup.sh.
Scripts in /etc/cron.hourly, cron.daily, cron.weekly and cron.monthly run at those intervals. File names must not contain dots on Debian (run-parts ignores them).
Who may use crontab is controlled by /etc/cron.allow and /etc/cron.deny.

One-off jobs with at

echo "/usr/local/bin/report.sh" | at 23:00
at now + 30 minutes <<< "systemctl restart app"
atq            # list pending jobs
atrm 3         # remove job 3

On systemd systems, timers are an alternative to cron with better logging: see systemctl.