Home / ubuntu / Questions / 92322
Accepted
ECII
Asked: 2012-01-03 14:55:22 +0800 CST

TIme of execution of daily anacron job

  • 772

I have set a daily anacron job, which runs form /etc/cron.daily. From the /etc/crontab I see it should run daily at 06:25 (or at start-up/reboot).

However when the date changes (00:00) and the computer is up, I dont want anacron to wait till 06:25. If the computer is up I would like to it to run the script as soon as the date changes (00:00). Does it make sense to add a cron job to run anacron @hourly?

Thank you very much

cron

5 Answers

  1. Best Answer

    I found how to do this and summarized it in my blogpost:

    If you want to change the behaviour of anacron to execute as soon as the day changes (and not wait till 7:30 as is the default behaviour) do the following:

    gksu gedit /etc/cron.d/anacron

    and add the last 2 lines (the last line will restart anacron every hour):

    01 0    * * *   root test -x /etc/init.d/anacron && /usr/sbin/invoke-rc.d anacron start >/dev/null
01 0    * * *   root start -q anacron || :
@hourly root start -q anacron || :
    • 7

  2. The answer by Khaled is not correct. Changing this line will not have an effect if anacron is installed (which it is, by default):

    25 6    * * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )

    If anacron exists, test -x /usr/sbin/anacron will return true, and prevent the second half of that line from running. The other answer (editing /etc/cron.d/anacron) is correct, since that's the config that will kick off anacron itself.

    • 6

  3. As of Ubuntu 19.10 (and maybe earlier) anacron is run using a systemd timer.

    Solution

    The way to change anacron execution time is with this command:

    sudo systemctl edit --full anacron.timer

    Then modify the line:

    OnCalendar=*-*-* 07..23:30

    What doesn't work

    As explained in other answers, editing /etc/crontab doesn't help.

    25 7    * * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )

    The part before the operator || only tests if anacron is installed, it doesn't execute anything. And the part after only get executed if the part before didn't complete successfully (lazy operator evaluation), which then would mean anacron isn't installed.

    Editing /etc/cron.d/anacron doesn't help either.

    30 7-23 * * *   root    [ -x /etc/init.d/anacron ] && if [ ! -d /run/systemd/system ]; then /usr/sbin/invoke-rc.d anacron start >/dev/null; fi

    The condition if [ ! -d /run/systemd/system ] prevents the script from running when systemd is installed.

    The correct way to change the execution time is by editing the systemd timer as explained at the begining.

    • 4

  4. as per other answers:

    edit the first two columns of /etc/cron.d/anacron to change the time anachron runs.

    (/etc/crontab values don't take effect due to the || ...)

    • 3

  5. You can just change the line:

    25 6    * * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )

    to read

    0 0    * * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )

    This will make the execution of daily cron jobs start at midnight.

    • 0