Cron batch job question

[Jorge Cocomess]

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

[Court Campbell]

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.

[John Poff · Accepted solution]

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

[Court Campbell]

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.

[John Poff]

Court,

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

JP

[Jorge Cocomess]

Great. I will give that try.

Thanks for your help.

Jorge

[Manuel Wolfshant]

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)

[Stuart Browne]

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.. ;)

[Jorge Cocomess]

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

[John Poff]

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