Unix – How to run a cron job every 5 minutes starting from a time other than 0 minutes

cronunix

I would like to have a script run every 5 minutes let's say starting from 13:02 so I can have another script runs every 5 minutes but starting from 13:04 so the second script runs two minutes after the start of the first job. How can I achieve this?

Best Answer

Syntax 1

*/5+2 * * * * 1st-script
*/5+4 * * * * 2nd-script

For future reference take a look at this online Cron Job Generator.

Syntax 2

Since there are several reports that the + syntax is not working on Ubuntu 14.04, here's a variation:

2-59/5 * * * * 1st-script
4-59/5 * * * * 2nd-script

This will result in the 1st script to run every 5 minutes starting with an offset of 2 minutes at the beginning of each hour and the 2nd script to behave the same with an offset of 4 minutes.

Related Solutions

Unix – How to list all cron jobs for all users

You would have to run this as root, but:

for user in $(cut -f1 -d: /etc/passwd); do crontab -u $user -l; done

will loop over each user name listing out their crontab. The crontabs are owned by the respective users so you won't be able to see another user's crontab w/o being them or root.

Edit if you want to know which user a crontab belongs to, use echo $user

for user in $(cut -f1 -d: /etc/passwd); do echo $user; crontab -u $user -l; done

Linux – How to instruct cron to execute a job every second week

Answer

Modify your Tuesday cron logic to execute every other week since the epoch.

Knowing that there are 604800 seconds in a week (ignoring DST changes and leap seconds, thank you), and using GNU date:

0 6 * * Tue expr `date +\%s` / 604800 \% 2 >/dev/null || /scripts/fortnightly.sh

Aside

Calendar arithmetic is frustrating.

@xahtep's answer is terrific but, as @Doppelganger noted in comments, it will fail on certain year boundaries. None of the date utility's "week of year" specifiers can help here. Some Tuesday in early January will inevitably repeat the week parity of the final Tuesday in the preceding year: 2016-01-05 (%V), 2018-01-02 (%U), and 2019-01-01 (%W).