I'm wondering: Why is the yum command still in the RHEL 8 RH124 course content (seen in Chapter 14)?
It has been replaced with dnf. When man yum, you get this:
When you man dnf, you get almost the exact same thing DNF(8) vs YUM(8), and that's about it.
As I stress using the man pages in my classes, I will be re-writing the content, referencing dnf instead of yum.
I do see that /etc/yum.repos.d/ is still used (there is no /etc/dnf.repos.d/).
I see that yum-config-manager (notice: 2 dashes) has been replaced with dnf config-manager (notice: 1 dash).
Perhaps the content should be updated to reflect that yum is now really dnf?
So, from Red Hat's perspective, yum is still the correct command for package management in RHEL 8. This was done for a number of reasons, in part because we did not want to change the tool name and scripted behavior relative to what our RHEL 7 users were familiar with (influenced by feedback from customers).
The truth is that yes, it's been implemented in RHEL 8 using dnf. However, at least for now, we continue teaching yum as the preferred command for RHEL 8 users. Note that the official documentation on installing packages and managing packaging modules also uses yum:
If you're on Fedora, then the story is different and that distribution prefers to use the dnf tools; it's one minor difference/distinction between the two distributions.
Interestingly, the link you provided is not the one that used in the official RH124 content (on Gilmore). That link is:
If you then go to Section 2, Installing software with yum, you see this:
On Red Hat Enterprise Linux 8, installing software is ensured by the new version of the YUM tool, which is based on the DNF technology (YUM v4).
Now, to be sure, talks a little more about yum / dnf and then continues with yum examples.
I get that.
My point is that a student who has just finished their studies and wants to take the certification exams won't have access to these nuanced web pages and points-of-view. They'll have the man pages.
man yum brings up the pages for dnf
man yum-config-manager brings up the pages for the DNF version (dnf config-manager)
man -k yum returns this (every line references DNF):
I've decided to cut to the chase and rewrite the content and labs on package management to teach directly to DNF.
It is easy enough to teach them that, if using RHEL 7, simply replace dnf with yum and it works the same (for the techniques being learned in RH124, it is a 1:1 replacement).
(With the exeption of dnf config-manager / yum-config-manager)
I do have a few of updates now that I've finished the chapter on package management.
1) dnf works fine throughout. It does not mess with the grading scripts -- because the outcome is what's important.
2) Unfortunately, you cannot tab-complete when using dnf (you can if you use yum).
3) The link that @bonnevil posted is in the RH124 content - in the section covering Application Streams and Modularity. The link I posted shows in all other sections.
As a complete aside: why do I hear Boy George in my head when I read "modularity"? Could it be because he says "Popularity breeds contempt" at the beginning of the long version of Do You Really Want to Hurt Me by Culture Club? For those that know me well, you know I'm really into music...