topic Re: cron problem in Operating System - HP-UX

cron problem

Jan Verheijen — Sat, 15 Feb 2003 09:30:14 GMT

We have a cron job to start every day except Sunday at 20:00 H.
Last Friday at 11:00 am the cron job started twice!
How is this possible?
Any suggestions?

Re: cron problem

Rajeev Shukla — Sat, 15 Feb 2003 12:02:41 GMT

Its not possible untill some one has changed...
1. The time of the system.
2. Changed the time Zone of the system.
3. Changed the cron entry itself.

Please have a look at all above three only these could be the problem or see the cron log to /var/adm/cron/log file to see the exact time the job started.

rajeev

Re: cron problem

S.K. Chan — Sat, 15 Feb 2003 18:22:57 GMT

In addition ..
If for some reason the timezone or time of your system is changed, the cron daemon must be restarted. Otherwise this can potentially cause it to run twice. Another thing that you may want to check is patch. Look for any cron related patch and make sure (if any) your system is uptodate on these patches.

Re: cron problem

Steven E. Protter — Sun, 16 Feb 2003 04:40:15 GMT

Can you upload the cron command line? The whole thing.

It might be what the others suggested. Or....

You are connected to a time server and someone adjusted the time on that server. Is xntpd running?

ps -ef | grep xntpd

Thinking further in my fever impaired mind I know how ntp works and that probably can't happen.

Could perhaps the date command been run on this server. Done at the right time, a small adjustment could trigger flakey behavior.

Are you current on cron patches?

SEP

Re: cron problem

john korterman — Sun, 16 Feb 2003 16:25:12 GMT

Hi Jan,
it is difficult to say, as I do not know how you have detected that the job was executed twice. I assume that the job was not simply executed from the command line; but could the job not be executed by two different users simultanously: cron or at job?
Anyway, if you have not already done it, check the general cron log, /var/adm/cron/log, which records which user did it, and when it started/stopped. Check also the content of each user's crontab and at files under /var/spool/cron/crontabs /var/spool/cront/atjobs in order to see any indication of the job in question having been executed by two different users.
If that is the case, but the time does not fit, then check whether the users in question have an individual setting of the TZ variable that differs from the general system setup.

regards,
John K.

Re: cron problem

Bruce Laughlin — Sun, 16 Feb 2003 16:36:56 GMT

Hi Jan,

It would be helpful if you would post the applicable cron job entry from the output of crontab -l for the user.

Thanks,
Bruce Laughlin
HPUX GSE

Re: cron problem

Fred Martin_1 — Tue, 18 Feb 2003 15:31:56 GMT

We had a similar thing happen and discovered that there were two timezone files on the system. On an HP-UX system I think it's at /etc/TIMEZONE.

Anyway on this Linux system there was one in the correct location, and a modified copy someplace else.

Someone changed a PATH setting, and suddenly the clocks where off, only discovered because a cron job misfired.

Turned out that the wrong timezone file was being accessed.

Anyway this is pretty remote and may not apply but it demonstrates how odd some this stuff can get.

Re: cron problem

Jan Verheijen — Fri, 21 Feb 2003 12:03:39 GMT

The cron job is :
# Kopieren ME10-macros
00 20 * * 1-6 /usr/local/bin/save_me10_macro

The date is now:
Fri Feb 21 13:00:32 MET 2003

xntpd is not running!

The job was runned twice by cron.

Re: cron problem

Pete Randall — Fri, 21 Feb 2003 12:07:52 GMT

Does /usr/local/bin/save_me10_macro, by any chance, resubmit itself via at?

I know - this is a shot in the dark but the logical explanations seem to have been exhausted a long time ago.

Pete

Re: cron problem

Robert-Jan Goossens — Fri, 21 Feb 2003 12:24:02 GMT

Hallo,

Could you check the date on process cron and compare it to the date of /var/spool/cron/crontabs/"user", maybe someone changed the cron with vi instead of crontab -e.

Hope it helps,

Robert-Jan.

Re: cron problem

Bruce Laughlin — Fri, 21 Feb 2003 13:03:54 GMT

Hi,

I'd take a look at the cron log file /var/adm/cron/log and see if there is anything interesting there.

Best regards,
Bruce Laughlin