In this blog we take a look at applying security updates to Red Hat Enterprise Linux 8. If you are used to using CentOS 8 then you may not have come across this feature as the package metadata is not available CentOS. If you have access to AWS you can use RHEL 8 in the cloud to practice this without the need of a Red Hat Subscription. The lab uses RHEL 8 in AWS.
The information here is more than you need for the RHCSA but is part of the certification for the EX415 security exam. Of course, if you are working with Red Hat then the more you know about their updates and security then the better you will be as an Admin.
When Applying Security Updates to Red Hat Enterprise Linux 8 we can use the yum or dnf command to list updates:
# yum updateinfo
This show a summary of the available updates. This show updates that are security related, bug fixes and enhancements. To drill down in this further we can look at only security updates:
# yum updateinfo --security
Or, even better we can list by the security level Critical, Important and so forth, just add the option –sec-severity and the required level:
# yum updateinfo --sec-severity Important
At this stage we still only see the summary information, we show 9 Important updates available. To be more useful we might want to dig inside the updates. To see the details of each of these updates we can add the info option to display the details page:
# yum updateinfo info --sec-severity Important
Each update will have an RHSA and Red Hat Security Advisory ID, we can search for a single ID. Choose an ID from you list as this update may not be needed on your system:
# yum updateinfo info RHSA-2020:2774
If we need to look atApplying Security Updates to Red Hat Enterprise Linux 8 and only this update we can try
# yum update --advisory RHSA-2020:2774