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I'm having trouble running a cron job at particular times during the day.

Will this crontab setting run the command at 3am, 6am, noon, 6pm, and 9pm?

0 3,6,12,18,21 * * * command
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migrated from stackoverflow.com Nov 7 '11 at 15:36

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marked as duplicate by Iain, masegaloeh, MadHatter, fukawi2, mdpc Mar 3 at 3:25

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3 Answers 3

up vote 5 down vote accepted

If that is in a user crontab (edited with crontab -e or crontab -e -u username), then yes.

If that is in the system crontab (/etc/crontab), it needs a username, i.e.

0 3,6,12,18,21 * * * run-as-this-username command
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the job already runs each hr. –  MB34 Nov 7 '11 at 16:06

Your cron specification is correct. If it doesn't appear to be running, it may be a PATH problem (i.e., your script references something in /usr/local/bin). If that's the case, you can stick something like

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

etc., at the top of your crontab to set the PATH for the cron jobs. (You can do something like "echo $PATH" at the command line to see the current PATH).

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path is not a problem –  MB34 Nov 7 '11 at 16:08

Yes, afaik, this should work. Did you already try it?

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no but it already runs using this: 0 * * * * command –  MB34 Nov 7 '11 at 16:06

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