Automatic YUM Updates with Yum-cron

This post will guide you how to use yum-cron to update system under CentOS/RHEL Linux. How do I configure yum automatic updates with yum-cron tool in Linux. How to set yum updates with yum-cron.

What is Yum-cron?

The yum-cron is an optional package starting from RHEL 6/CentOS 6 and it is a yum plugin.
yum-cron is a simple way to call yum commands from cron. It provides configuration to keep repository metadata up to date, and to check for, download, and apply updates.

Install yum-cron

If you want to setup automatic yum updates with yum-cron, you need to install the yum-cron package firstly. Type the following command:

# yum install yum-cron

Outputs:

[root@devops ~]# yum install yum-cron
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: centos.ustc.edu.cn
* extras: mirrors.huaweicloud.com
* updates: mirrors.aliyun.com
Resolving Dependencies
--> Running transaction check
---> Package yum-cron.noarch 0:3.4.3-158.el7.centos will be installed
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
yum-cron noarch 3.4.3-158.el7.centos base 63 k

Transaction Summary
================================================================================
Install 1 Package

Total download size: 63 k
Installed size: 51 k
Is this ok [y/d/N]: y
Downloading packages:
yum-cron-3.4.3-158.el7.centos.noarch.rpm | 63 kB 00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : yum-cron-3.4.3-158.el7.centos.noarch 1/1
Verifying : yum-cron-3.4.3-158.el7.centos.noarch 1/1

Installed:
yum-cron.noarch 0:3.4.3-158.el7.centos

Complete!

Start Yum-cron Service

After installed yum-cron package, you need to start the yum-cron service.

For CentOS 7/RHEL 7 Linux:

# systemctl start yum-cron.service

Outputs:

[root@devops ~]# systemctl start yum-cron
[root@devops ~]# systemctl status yum-cron
yum-cron.service - Run automatic yum updates as a cron job
Loaded: loaded (/usr/lib/systemd/system/yum-cron.service; enabled; vendor preset: disabled)
Active: active (exited) since Sun 2018-09-16 11:14:36 EDT; 2s ago
Process: 3579 ExecStart=/bin/touch /var/lock/subsys/yum-cron (code=exited, status=0/SUCCESS)
Main PID: 3579 (code=exited, status=0/SUCCESS)

Sep 16 11:14:36 devops systemd[1]: Starting Run automatic yum updates as a .....
Sep 16 11:14:36 devops systemd[1]: Started Run automatic yum updates as a c...b.
Hint: Some lines were ellipsized, use -l to show in full.

For CentOS 6/RHEL 6 Linux:

Type the following command:

# service yum-cron start

Configure Yum-cron

You need to edit the configuration file of yum-cron, and it is located in /etc/yum/yum-cron.conf.

For CentOS 6/RHEL 6 Linux:

Adding the below line into the file:

MAILTO=osetc@gmail.com
YUM_PARAMETER=kernel* http*

Note: The YUM_PARAMETER variable is used to exclude packages using yum-cron to update the system. So it won’t update the kernel and http packages.

For CentOS 7/RHEL 7 Linux:

Adding the below line into the file:
MAILTO=osetc@gmail.com
exclude=kernel* http*

Then save and close the file.

You still need to restart the yum-cron service.

Type the following command:

# systemctl restart yum-cron

Or

# service yum-cron restart

By default, the yum-cron tool will be run daily based on the yum-daily.cron job. Let’s see this cron job.

[root@devops ~]# cat /etc/cron.daily/0yum-daily.cron
#!/bin/bash
# Only run if this flag is set. The flag is created by the yum-cron init
# script when the service is started -- this allows one to use chkconfig and
# the standard "service stop|start" commands to enable or disable yum-cron.
if [[ ! -f /var/lock/subsys/yum-cron ]]; then
exit 0
fi
# Action!
exec /usr/sbin/yum-cron

If you want to get more information about the yum-cron, just see the man page of yum-cron.

# man yum-cron