CentOS / RHEL Configure Yum Automatic Update Retrieval and Installation

The yum command line tool is used to install and update software packages under RHEL / CentOS Linux server. I know how to apply updates using yum update command line, but I'd like to use cron to manually update packages where appropriate. How do I configure yum to install software patches / updates automatically with cron?

You can use yum-updatesd service provided with CentOS / RHEL servers. However, this service provides a few overheads. You can create daily or weekly updates with the following shell script. Create

• /etc/cron.daily/yumupdate.sh to apply updates one a day.
• /etc/cron.weekly/yumupdate.sh to apply updates once a week.

Sample shell script to update system

A shell script that instructs yum to update any packages it finds via cron:

#!/bin/bash
YUM=/usr/bin/yum
$YUM -y -R 120 -d 0 -e 0 update yum
$YUM -y -R 10 -e 0 -d 0 update
 

(Code listing -01: /etc/cron.daily/yumupdate.sh)

Where,

1. First command will update yum itself and next will apply system updates.
2. -R 120 : Sets the maximum amount of time yum will wait before performing a command
3. -e 0 : Sets the error level to 0 (range 0 - 10). 0 means print only critical errors about which you must be told.
-d 0 : Sets the debugging level to 0 - turns up or down the amount of things that are printed. (range: 0 - 10).
4. -y : Assume yes; assume that the answer to any question which would be asked is yes.

Make sure you setup executable permission:
# chmod +x /etc/cron.daily/yumupdate.sh

Recommend readings:

1. yum man page
2. yum command: Update / Install Packages under Redhat Enterprise / CentOS Linux Version 5.x
3. How do I add jobs to cron under Linux or UNIX oses?

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