topic Re: Cron batch job question in Operating System - Linux

Cron batch job question

Jorge Cocomess — Tue, 10 Apr 2007 13:37:08 GMT

Hi,

I have this cron job that runs every 15 minutes. Now, I would like to have it run 4 times a day, starting at 6:30 AM. How would I change the time format in the cron job?

Thank you in advance.

Jorge

Re: Cron batch job question

Court Campbell — Tue, 10 Apr 2007 13:50:01 GMT

a simple solution would be to add 4 separate cron entries in /etc/crontab. set each of them to run at the specified times that you want.

Re: Cron batch job question

John Poff — Tue, 10 Apr 2007 13:52:17 GMT

Hi,

One way to do it is:

30 6,12,18,00 * * * /some/batch/script

which would run it at 6:30am, 12:30pm, 6:30pm, and 12:30am.

Try a 'man 5 crontab' to arrive at true cron job enlightenment.

JP

Re: Cron batch job question

Court Campbell — Tue, 10 Apr 2007 13:58:51 GMT

Use John's suggestion. It is much cleaner. I have no excuse for not suggesting that in the first place. but as I always say, there is more that one way to do it.

Re: Cron batch job question

John Poff — Tue, 10 Apr 2007 14:55:14 GMT

Court,

I made my suggestion based on the fact that I'm too old and too lazy to type in four lines. :)

JP

Re: Cron batch job question

Jorge Cocomess — Tue, 10 Apr 2007 15:12:21 GMT

Great. I will give that try.

Thanks for your help.

Jorge

Re: Cron batch job question

Manuel Wolfshant — Tue, 10 Apr 2007 19:08:18 GMT

For what is worth,cron knows about steps, so if you have a regular interval between the runs, you could use
30 6/6 * * * /some/batch/script

Which translates into start at 6:30 (the first 6 in the hours field plus the minutes field) and run after every 6hrs (24hrs/4= 6 hrs => second 6 in the hours field)

Re: Cron batch job question

Stuart Browne — Tue, 10 Apr 2007 19:21:21 GMT

Just a caution for the previous post.

This will work fine on the cron daemon used on most Linux distributions for the past 10 years or so (go Vixie crond!); just be careful when you use other OS's. Some of them don't have a cron daemon as flexable.

Other things to note are things like '/etc/crontab', and '/etc/cron.d/' on top of user crontab's (modified using '/usr/bin/crontab -e'.

So very very useful, especially for distributing jobs to other servers.. ;)

Re: Cron batch job question

Jorge Cocomess — Wed, 11 Apr 2007 11:51:37 GMT

Hi,

I made the changes like John had recommended. However, the cron job is not running though. I can't seem to see any syntax errors. Although, is there a space after the comma (30 06,10,13,19, ei)>>>

Please help.

Thanks,
Jorge

Re: Cron batch job question

John Poff — Wed, 11 Apr 2007 14:48:07 GMT

Try it without any spaces in the list for the hours, and try redirecting output to a file:

30 6,12,18,00 * * * /some/batch/script >>/var/tmp/script.out 2>&1

Also, you might want to check permissions and ownership of your script, as well as setting the PATH explicitly inside of the script.

JP

Re: Cron batch job question

Rob Leadbeater — Wed, 11 Apr 2007 16:46:16 GMT

You might also want to check cron's log for errors, which is (usually) in /var/log/cron

Regards,

Rob

Re: Cron batch job question

Court Campbell — Thu, 12 Apr 2007 12:31:32 GMT

see if /etc/cron.allow exists. if it does make sure the account running the job is located in the file. otherwise see if the account is listed in /etc/cron.deny and remove it from that file. Just a hunch.

Re: Cron batch job question

Court Campbell — Thu, 12 Apr 2007 12:32:28 GMT

OK, i am an idiot. You were are already running the jobs successfully. Ignore my last post.