Question about cron timing - BSD

This is a discussion on Question about cron timing - BSD ; Hello, Before I begin, if this is not of general interest please feel free to e-mail your suggestions to me. Reply-To: is properly set to facilitate that. I have a question about cron's timing. Some strange things have been happening ...

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  1. Question about cron timing

    Hello,

    Before I begin, if this is not of general interest please feel free
    to e-mail your suggestions to me. Reply-To: is properly set to
    facilitate that.

    I have a question about cron's timing. Some strange things have
    been happening lately as far as timing is concerned.

    I've looked in /var/log/cron and find that the time stamps are
    really strange. If I edit with crontab -e, the log entry shows th
    proper time stamp but for anything that cron runs, it shows a time
    stamp for the hour before. Here's a short snippet from the log file:

    Mar 23 14:50:00 sorsby /usr/sbin/cron[30592]: (crs) CMD /home/crs/bin/getmail
    Mar 23 15:52:56 sorsby crontab[30613]: (root) BEGIN EDIT (root)
    Mar 23 15:53:23 sorsby crontab[30613]: (root) REPLACE (root)
    Mar 23 15:53:23 sorsby crontab[30613]: (root) END EDIT (root)
    Mar 23 14:54:00 sorsby /usr/sbin/cron[131]: (root) RELOAD (tabs/root)
    Mar 23 14:55:00 sorsby /usr/sbin/cron[30618]: (root) CMD (/usr/libexec/atrun)
    Mar 23 14:55:00 sorsby /usr/sbin/cron[30619]: (crs) CMD (/home/crs/bin/getmail

    Notice that cron ran getmail at what it thinks is 14:50. A couple
    minutes later, I edited root's crontab and it shows that event at
    the correct time, 51:52:56. Then, after my edit, it reverts back
    to the incorrect time. It's as though all of the system except
    cron is on Daylight Saving Time but cron is on standard time.

    Does cron *not* use the same clock as the rest of the system?
    I tried looking in _Unix System Administration Handbook_ by Nemeth,
    et al. but couldn't find anything about how cron is actually timed.

    How does one tell cron that we're on daylight saving time now?
    (And, yes, I did fetch the time-zone configuration file from
    ftp://elsie.nci.nih.gov/pub/tzdata2007b.tar.gz and perform the
    steps per:
    http://articles.techrepublic.com.com...7-6163042.html
    and, as far as I can tell, everything is running on DST -- *except*
    cron.

    What must I do to tell cron to run at the same time as the rest of
    the system? Surely it isn't necessary to reboot the system to
    convince cron that the time's really an hour later than it thinks
    it is... Would that even do it?

    For what it's worth I'm running freeBSD 4.11 (don't ask) as
    distributed on the CDROM.

    Many thanks for any help and kindest regards,

    Charlie
    --
    Charlie Sorsby
    crs@swcp.com
    Edgewood, NM 87015
    USA

  2. Re: Question about cron timing

    In article <0m1ed4-s8u.ln1@sorsby.org>, Charlie Sorsby wrote:
    >Hello,
    >
    >Before I begin, if this is not of general interest please feel free
    >to e-mail your suggestions to me. Reply-To: is properly set to
    >facilitate that.
    >
    >I have a question about cron's timing. Some strange things have
    >been happening lately as far as timing is concerned.
    >
    >I've looked in /var/log/cron and find that the time stamps are
    >really strange. If I edit with crontab -e, the log entry shows th
    >proper time stamp but for anything that cron runs, it shows a time
    >stamp for the hour before. Here's a short snippet from the log file:
    >
    >Mar 23 14:50:00 sorsby /usr/sbin/cron[30592]: (crs) CMD /home/crs/bin/getmail
    >Mar 23 15:52:56 sorsby crontab[30613]: (root) BEGIN EDIT (root)
    >Mar 23 15:53:23 sorsby crontab[30613]: (root) REPLACE (root)
    >Mar 23 15:53:23 sorsby crontab[30613]: (root) END EDIT (root)
    >Mar 23 14:54:00 sorsby /usr/sbin/cron[131]: (root) RELOAD (tabs/root)
    >Mar 23 14:55:00 sorsby /usr/sbin/cron[30618]: (root) CMD (/usr/libexec/atrun)
    >Mar 23 14:55:00 sorsby /usr/sbin/cron[30619]: (crs) CMD (/home/crs/bin/getmail
    >
    >Notice that cron ran getmail at what it thinks is 14:50. A couple
    >minutes later, I edited root's crontab and it shows that event at
    >the correct time, 51:52:56. Then, after my edit, it reverts back
    >to the incorrect time. It's as though all of the system except
    >cron is on Daylight Saving Time but cron is on standard time.
    >
    >Does cron *not* use the same clock as the rest of the system?
    >I tried looking in _Unix System Administration Handbook_ by Nemeth,
    >et al. but couldn't find anything about how cron is actually timed.
    >
    >How does one tell cron that we're on daylight saving time now?
    >(And, yes, I did fetch the time-zone configuration file from
    >ftp://elsie.nci.nih.gov/pub/tzdata2007b.tar.gz and perform the
    >steps per:
    >http://articles.techrepublic.com.com...7-6163042.html
    >and, as far as I can tell, everything is running on DST -- *except*
    >cron.
    >
    >What must I do to tell cron to run at the same time as the rest of
    >the system? Surely it isn't necessary to reboot the system to
    >convince cron that the time's really an hour later than it thinks
    >it is... Would that even do it?
    >
    >For what it's worth I'm running freeBSD 4.11 (don't ask) as
    >distributed on the CDROM.
    >
    >Many thanks for any help and kindest regards,
    >
    >Charlie
    >--
    >Charlie Sorsby
    > crs@swcp.com
    > Edgewood, NM 87015
    > USA


    Have you run /usr/ports/misc/zoneinfo to take of care of the
    new time zones that went into effect a week or so ago?

    It's a really quick fix.

    Bill
    --
    Bill Vermillion - bv @ wjv . com

  3. Re: Question about cron timing

    In article <0m1ed4-s8u.ln1@sorsby.org>, Charlie Sorsby wrote:
    >Hello,
    >
    >Before I begin, if this is not of general interest please feel free
    >to e-mail your suggestions to me. Reply-To: is properly set to
    >facilitate that.
    >
    >I have a question about cron's timing. Some strange things have
    >been happening lately as far as timing is concerned.
    >
    >I've looked in /var/log/cron and find that the time stamps are
    >really strange. If I edit with crontab -e, the log entry shows th
    >proper time stamp but for anything that cron runs, it shows a time
    >stamp for the hour before. Here's a short snippet from the log file:
    >
    >Mar 23 14:50:00 sorsby /usr/sbin/cron[30592]: (crs) CMD /home/crs/bin/getmail
    >Mar 23 15:52:56 sorsby crontab[30613]: (root) BEGIN EDIT (root)
    >Mar 23 15:53:23 sorsby crontab[30613]: (root) REPLACE (root)
    >Mar 23 15:53:23 sorsby crontab[30613]: (root) END EDIT (root)
    >Mar 23 14:54:00 sorsby /usr/sbin/cron[131]: (root) RELOAD (tabs/root)
    >Mar 23 14:55:00 sorsby /usr/sbin/cron[30618]: (root) CMD (/usr/libexec/atrun)
    >Mar 23 14:55:00 sorsby /usr/sbin/cron[30619]: (crs) CMD (/home/crs/bin/getmail
    >
    >Notice that cron ran getmail at what it thinks is 14:50. A couple
    >minutes later, I edited root's crontab and it shows that event at
    >the correct time, 51:52:56. Then, after my edit, it reverts back
    >to the incorrect time. It's as though all of the system except
    >cron is on Daylight Saving Time but cron is on standard time.
    >
    >Does cron *not* use the same clock as the rest of the system?
    >I tried looking in _Unix System Administration Handbook_ by Nemeth,
    >et al. but couldn't find anything about how cron is actually timed.
    >
    >How does one tell cron that we're on daylight saving time now?
    >(And, yes, I did fetch the time-zone configuration file from
    >ftp://elsie.nci.nih.gov/pub/tzdata2007b.tar.gz and perform the
    >steps per:
    >http://articles.techrepublic.com.com...7-6163042.html
    >and, as far as I can tell, everything is running on DST -- *except*
    >cron.
    >
    >What must I do to tell cron to run at the same time as the rest of
    >the system? Surely it isn't necessary to reboot the system to
    >convince cron that the time's really an hour later than it thinks
    >it is... Would that even do it?
    >
    >For what it's worth I'm running freeBSD 4.11 (don't ask) as
    >distributed on the CDROM.
    >
    >Many thanks for any help and kindest regards,


    *SOME* applications get the timezone info at program _start-up_ only.
    they don't expect the 'zoneinfo' file to change out from under them.
    They _do_ adjust time translation, according to the specifications they
    read in, at program start-up.

    Shut down the daemon and re-start it -- this should fix the problem.

    Re-boot _not_ required.



  4. Re: Question about cron timing

    On Fri, 23 Mar 2007, in the Usenet newsgroup comp.unix.bsd.freebsd.misc, in
    article <0m1ed4-s8u.ln1@sorsby.org>, Charlie Sorsby wrote:

    > If I edit with crontab -e, the log entry shows th
    >proper time stamp but for anything that cron runs, it shows a time
    >stamp for the hour before. Here's a short snippet from the log file:


    Yes - they are different processes - as the log shows

    >Mar 23 14:54:00 sorsby /usr/sbin/cron[131]: (root) RELOAD (tabs/root)


    Reloading the _crontab_

    >Does cron *not* use the same clock as the rest of the system?


    Yes

    >How does one tell cron that we're on daylight saving time now?


    Same way everyone else does - by computing the time plus the offset.

    >(And, yes, I did fetch the time-zone configuration file from
    >ftp://elsie.nci.nih.gov/pub/tzdata2007b.tar.gz and perform the
    >steps per:
    >http://articles.techrepublic.com.com...7-6163042.html
    >and, as far as I can tell, everything is running on DST -- *except*
    >cron.


    Ah, one of the joys of living in Arizona where I don't have to put
    up with this crap. Anyway, when did you replace the files, compared
    to when did the cron daemon _start_ (not reload, but start)? Some
    processes only look at the tzset information when they start. As a
    shot, try sending cron a -HUP (kill 30592 -HUP) and see if that
    cures it - and if not, try stopping and starting the daemon.

    Old guy


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