Markku Kolkka wrote:
What does it actually mean for yum to be "on"?
I would have thought a daily (or rather nightly) cron job running "yum -y update" would be what most people would want,
That's exactly what you get when the yum pseudo-service is on. It sets a flag that is checked by the yum.cron script in /etc/cron.daily
OK, thanks. I saw the flag in the yum.cron script, but didn't realise its purpose.
Isn't this a slightly odd way to do things? I always assumed that chkconfig is just for starting daemons.
No, chkconfig is for setting/displaying which daemons run automatically in each runlevel. It doesn't actually start or stop anything itself (well, actually it does for xinetd-based services...). The "service" utility can be used to start or stop a daemon at any time (it's just a shorthand way of running the daemon's initscript from /etc/rc.d/init.d).
The way the yum service works is that there is a cron job to call yum every night. It does this whether nightly yum updates are enabled or not. The first thing the cron job does is to check whether nightly updates are enabled, and it exits immediately if they're not. This method means that yum does not have to run as a daemon itself, saving both the effort of implementing this feature in yum and a bit of memory on each system it would be running on - as it stands, yum only consumes resources when you're actually running it.
Paul.
