[CentOS] Questions about yum-cron

Sun Jun 3 13:56:13 UTC 2018
Pete Biggs <pete at biggs.org.uk>

> 2. It looks like editing /etc/yum/yum-cron.conf affects a *daily*
> operation of yum-cron, whereas editing /etc/yum/yum-cron-
> hourly.conf provides hourly operations. The documentation is not very
> clear about this, and I'm a little confused here. In other words,
> yum-cron.conf affects /etc/cron.daily/0yum-daily.cron, and
> yum-cron-hourly.conf affects /etc/cron.hourly/0yum-hourly.cron.

Yes. All the cron scripts do is to execute yum-cron with an optional
config script as an argument; if no config file is given, it uses the
default (/etc/yum/yum-cron.conf). 'man yum-cron' tells you this.

> I only really need yum-cron to run once a day, which would be
> sufficient.

The hourly version (in the default install) does nothing other than
update the caches.

>  That being said, I can't figure out at what time it
> launches. All my users are in France, so ideally the daily yum-cron
> should be launched somewhere between 04:00 and 05:00 AM, since updating
> a package like httpd would restart the corresponding processes and kick
> online users out. I can't seem to figure out a way to define the exact
> time at which the daily yum-cron is being launched, since this doesn't
> seem to be controlled by standard crontab.

The scripts in /etc/cron.daily are run via anacron with a configuration
 file of /etc/anacrontab. The exact time the jobs are run are not
specified and are variable depending on what the machine is doing (and
a random delay). But you can impose time limits on when the jobs can be

cron.hourly is different and executed via the normal cron system
(config is in /etc/cron.d/0hourly)