CronDrive

Test a cron expression

See what it means and when it runs next, in your time zone.

It's 20:30 there now (UTC+00:00).

Which time zone do I choose?

The time zone of the server where the crontab runs, which may not be yours. To see it, run this on the server:

timedatectl | grep "Time zone"

If the crontab sets CRON_TZ, choose that one.

Every day at 02:00

0 minute
2 hour
* day
* month
* weekday

Next runs (UTC)

  1. Sat 17 Oct, 02:00
  2. Sun 18 Oct, 02:00
  3. Mon 19 Oct, 02:00
  4. Tue 20 Oct, 02:00
  5. Wed 21 Oct, 02:00
  6. Thu 22 Oct, 02:00
  7. Fri 23 Oct, 02:00
  8. Sat 24 Oct, 02:00
  9. Sun 25 Oct, 02:00
  10. Mon 26 Oct, 02:00

Know when it doesn't run

CronDrive emails you, or posts to Slack, when a job with this schedule fails, or doesn't start or finish on time. Free for up to 15 jobs.

What you'd see with this schedule

An example with the last runs of this schedule and made-up results: one failed and one didn't run.

Times in UTC.

Due
Thu 15 Oct, 02:00 On time Started 02:00, finished 02:13, took 13 min.
Wed 14 Oct, 02:00 Didn't run Alerts sent at 02:05 and 02:30.
Tue 13 Oct, 02:00 On time Started 02:00, finished 02:14, took 14 min.
Mon 12 Oct, 02:00 Failed with code 1 Alert sent at 02:04. Started 02:00, finished 02:04, took 4 min.
Sun 11 Oct, 02:00 On time Started 02:00, finished 02:13, took 13 min.
Sat 10 Oct, 02:00 On time Started 02:00, finished 02:14, took 14 min.

The alert of the failed run

Email from CronDrive, Mon 12 Oct, 02:04

Failed (exit code 1): "Your job"

The job "Your job" failed with exit code 1.

If you connect Slack, the same message goes to your channel.

The change in your crontab

0 2 * * * curl -fsS -m 10 https://job.crondrive.com/uG2Exw/start/$$; /path/to/job.sh; curl -fsS -m 10 https://job.crondrive.com/uG2Exw/end/$?/$$

Two calls around your command, in the same line. Your job's line comes with its own token.

Monitor this schedule

Format

Cron is driven by a crontab (cron table) file, a configuration file that specifies shell commands to run periodically on a given schedule. On Linux you can run crontab -e to edit it.

Each line has a cron expression made of five fields, followed by a shell command to execute. A * means every value; 1,5 is a list, 1-5 a range and */5 a step.

* minute 0-59
* hour 0-23
* day 1-31
* month 1-12
* weekday 0-6, Sunday is 0

Examples

Expression Description
* * * * * Every minute
*/5 * * * * Every 5 minutes
*/10 * * * * Every 10 minutes
*/15 * * * * Every 15 minutes
*/30 * * * * Every 30 minutes
0 * * * * Every hour
0 */2 * * * Every 2 hours
0 */6 * * * Every 6 hours
0 */12 * * * Every 12 hours
0 0 * * * Every day at 00:00
0 8 * * 1-5 At 08:00 on Monday through Friday
0 0 * * 1 At 00:00 on Monday
0 0 * * 0 At 00:00 on Sunday
0 0 1 * * At 00:00 on day 1 of the month
0 */8 * * * Every 8 hours
1,5 * * * * At minutes 1 and 5 of every hour
1-5 * * * * At minutes 1 through 5 of every hour
0 2 * * * Every day at 02:00
0 1 * * 1,2 At 01:00 on Monday and Tuesday
30 9-17 * * 1-5 Every hour from 09:30 to 17:30 on Monday through Friday
0 0 */5 * * At 00:00 every 5 days