Cron Expression Cheatsheet

Quick reference for cron syntax covering field syntax, special strings, field values, time examples, system tasks, backup tasks, environment, and troubleshooting

60 commands

* * * * * command

Run every minute (min hour day month weekday)

* * * * * /path/to/script.sh

crontab -e

Edit current user's crontab

crontab -e

crontab -l

List current user's crontab

crontab -l

crontab -r

Remove current user's crontab

crontab -r

crontab -u {user} -e

Edit crontab for specific user

sudo crontab -u www-data -e

crontab -u {user} -l

List crontab for specific user

sudo crontab -u www-data -l

/etc/crontab

System crontab file (with user field)

sudo vi /etc/crontab

/etc/cron.d/

Additional cron job definition directory

ls /etc/cron.d/

@reboot

Run once at system startup

@reboot /path/to/startup.sh

@yearly / @annually

Run once a year (Jan 1, 00:00)

@yearly /path/to/yearly-report.sh

@monthly

Run once a month (1st, 00:00)

@monthly /path/to/monthly-cleanup.sh

@weekly

Run once a week (Sunday, 00:00)

@weekly /path/to/weekly-backup.sh

@daily / @midnight

Run once a day (00:00)

@daily /path/to/daily-task.sh

@hourly

Run once an hour (at :00)

@hourly /path/to/hourly-check.sh

* (asterisk)

Match all values

* * * * * → every minute

, (comma)

List multiple values

1,15,30 * * * * → at :01, :15, :30

- (hyphen)

Range of values

1-5 * * * * → minutes 1 through 5

/ (slash)

Step values (intervals)

*/5 * * * * → every 5 minutes

分: 0-59

Minute field range

30 * * * * → at :30 every hour

時: 0-23

Hour field range

0 9 * * * → at 9:00 AM

日: 1-31

Day of month field range

0 0 1 * * → 1st of every month

月: 1-12 / JAN-DEC

Month field range

0 0 1 1 * → January 1st

曜日: 0-7 / SUN-SAT

Day of week range (0 and 7 = Sunday)

0 0 * * 1 → every Monday

*/5 * * * *

Run every 5 minutes

*/5 * * * * /path/to/check.sh

*/15 * * * *

Run every 15 minutes

*/15 * * * * /path/to/monitor.sh

0 * * * *

Run at the start of every hour

0 * * * * /path/to/hourly.sh

0 */2 * * *

Run every 2 hours

0 */2 * * * /path/to/bihourlyjob.sh

0 9 * * *

Run daily at 9:00 AM

0 9 * * * /path/to/morning.sh

0 9-17 * * 1-5

Run hourly 9-17 on weekdays

0 9-17 * * 1-5 /path/to/business-hours.sh

30 2 * * *

Run daily at 2:30 AM

30 2 * * * /path/to/nightly.sh

0 0 * * 0

Run every Sunday at midnight

0 0 * * 0 /path/to/weekly.sh

0 0 1 * *

Run on the 1st of every month

0 0 1 * * /path/to/monthly.sh

0 0 1 1 *

Run on January 1st every year

0 0 1 1 * /path/to/newyear.sh

*/5 * * * * ... >/dev/null 2>&1

Run and discard output

*/5 * * * * /path/to/script.sh >/dev/null 2>&1

0 3 * * * ... >> /var/log/cron.log 2>&1

Append output to log file

0 3 * * * /path/to/task.sh >> /var/log/cron.log 2>&1

0 2 * * * apt-get update

Update package list daily at 2 AM

0 2 * * * apt-get update -qq

0 4 * * * find /tmp -mtime +7 -delete

Delete temp files older than 7 days

0 4 * * * find /tmp -type f -mtime +7 -delete

*/10 * * * * /usr/bin/certbot renew

Check SSL certificate renewal

0 3 * * * /usr/bin/certbot renew --quiet

0 6 * * * systemctl restart nginx

Restart Nginx daily at 6 AM

0 6 * * * systemctl restart nginx

*/2 * * * * /path/to/healthcheck.sh

Run health check every 2 minutes

*/2 * * * * /path/to/healthcheck.sh

0 1 * * * mysqldump ...

MySQL backup daily at 1 AM

0 1 * * * mysqldump -u root dbname > /backup/db_$(date +\%F).sql

0 2 * * * pg_dump ...

PostgreSQL backup daily at 2 AM

0 2 * * * pg_dump -U postgres dbname > /backup/pg_$(date +\%F).sql

0 3 * * * tar czf ...

Archive directory daily at 3 AM

0 3 * * * tar czf /backup/www_$(date +\%F).tar.gz /var/www

0 4 * * * rsync -avz ...

Remote sync backup daily at 4 AM

0 4 * * * rsync -avz /data/ user@backup:/backup/data/

0 0 * * 0 find /backup -mtime +30 -delete

Delete backups older than 30 days weekly

0 0 * * 0 find /backup -type f -mtime +30 -delete

0 5 * * * aws s3 sync ...

Sync backup to S3 daily at 5 AM

0 5 * * * aws s3 sync /backup s3://my-bucket/backup/

SHELL=/bin/bash

Set cron execution shell

SHELL=/bin/bash

PATH=...

Explicitly set PATH

PATH=/usr/local/bin:/usr/bin:/bin

MAILTO=user@example.com

Set email for cron output

MAILTO=admin@example.com

MAILTO=""

Disable cron email output

MAILTO=""

HOME=/home/user

Set home directory

HOME=/home/deploy

CRON_TZ=timezone

Set cron timezone

CRON_TZ=Asia/Tokyo

grep CRON /var/log/syslog

Check cron logs

grep CRON /var/log/syslog | tail -20

journalctl -u cron

View cron logs via systemd

journalctl -u cron --since today

systemctl status cron

Check cron service status

systemctl status cron

systemctl restart cron

Restart cron service

sudo systemctl restart cron

run-parts --test /etc/cron.d/

Test-run scripts in cron.d

run-parts --test /etc/cron.daily/

date

Check server current time

date && timedatectl

which {command}

Check full path of command

which python3

env -i /bin/bash -c 'command'

Test command in minimal environment

env -i /bin/bash -c '/path/to/script.sh'