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What would be the crontab entry look like for a job that runs on the first day of every third month?

gWaldo
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haim evgi
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4 Answers4

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The following will run script on the 1st of Jan, Apr, Jul and Oct at 03:30

30 03 01 Jan,Apr,Jul,Oct * /path/to/script

Alternatively, but less obvious

30 03 01 */3 * /path/to/script

Will run every three months at 03:30 on the 1st of Jan,Apr,Jul and Oct.

Richard Holloway
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    +1: I always thought the / notation was the MOST obvious...I use it wherever possible. (Words in the scheduling part of the crontab freak me out...I'd do: "0 0 1 3,6,9,12 * /path/to/script.bash" if I couldn't do /3) – Satanicpuppy Apr 06 '10 at 14:27
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    wouldn't */3 be every four months (12/3 = 4)? – warren Feb 29 '16 at 21:45
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    @warren No it would not. The logic here is more of a mod truth statement. Ex: if(12%3 == 0): run_script(). I thought about this as well! Great question. – Goahnary Dec 28 '16 at 19:13
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    @Goahnary I realized that a while after I asked for the clarification, too :) – warren Dec 28 '16 at 19:15
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    @warren it really should be a mod operator rather than a division. But oh well ¯_(ツ)_/¯ – Goahnary Dec 28 '16 at 19:17
  • @Goahnary So I think it will run on Mar, Jun, Sep, & Dec right rather than in answer: 'Jan,Apr,Jul,Oct' – bharat Jun 04 '19 at 05:09
8

Wikipedia has a nice explanation about how to configure Cron.

For your specific case you could run a Cron Expression to run every 3 months- obviously change the months to suit your schedule. 

0 0 1 JAN,APR,JUL,OCT  * /path/to/script.bash
David Spillett
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Jon Rhoades
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3

The accepted answer is good, thou I'd use an alternative with simpler numbers and easier to read: https://crontab.guru

0 0 1 */3 *

Read like this: “At 00:00 on day-of-month 1 in every 3rd month.”

Josiel Faleiros
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0

For JIRA (and other 6 digit cron expressions):

0 0 0 1 JAN,APR,JUL,OCT ?

lobi
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