I host this site on a Linode VPS running CentOS 6 and wanted a way to be automatically notified of any updates that are available. In a previous life I was a RHEL 5 system administrator and the tool for doing this was
yumupdatesd, though I never personally used it — I like to control when and what updates are installed in a production environment. That tool no longer exists in RHEL 6 and has been replaced with
Install and configure yum-cron
The first thing to do is install the package if it is not already installed.
sudo yum install yum-cron
If you list the package contents with
rpm -ql yum-cron you’ll see it installs a shell script run by
cron, an init script, a config file, two yum shell files, and the man pages.
/etc/cron.daily/0yum.cron /etc/rc.d/init.d/yum-cron /etc/sysconfig/yum-cron /etc/yum/yum-daily.yum /etc/yum/yum-weekly.yum /usr/share/doc/yum-cron-3.2.29 /usr/share/doc/yum-cron-3.2.29/COPYING /usr/share/man/man8/yum-cron.8.gz
The main configuration file is
/etc/sysconfig/yum-cron. The default settings will check for and install updates every day1. You can change this as well as exclude certain updates if you wish. I would also recommend setting up email notifications.
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Since the scripts in
/etc/cron.daily are run according to the settings in
/etc/anacrontab, the exact time the updates run will vary. This time is further randomized by the
$RANDOMWAIT variable in
/etc/sysconfig/yum-cron. That’s a long way of saying don’t expect the job to run at the exact same time every day. I have found the job usually runs between 0330 and 0430.
If you want more precise control over when the job runs, move
1. You may then schedule this job using
crontab -e as
I made a few slight changes so the from address would look nicer.
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Once you’re happy with the configuration, don’t forget to start the service and enable it.
sudo chkconig yum-cron on sudo service yum-cron start
Setting up email notification
In order to receive email notifications, you will need a mail transport agent installed and running. I use
postfix with mostly default settings.
sudo yum install postfix
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Once you are happy with your settings, start and enable the service.
sudo chkconig postfix on sudo service postfix start
A nice thing about
yum-cron is that it will not send you an email if there are no updates.
Testing your configuration
To test if
postfix is working properly, just send yourself a test message.
echo "This is a test message" | mail -s "Testing postfix" firstname.lastname@example.org
You can check
/var/log/maillog to see what’s happening.
To test the
0yum.cron script without having to wait for the scheduled time to roll around, change the
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It seems like a lot just to configure automatic updates, but alas nothing is ever as simple as it seems. Computers are only as smart as the people programming and configuring them. Enjoy your magical new updater!