$ ssh me@myol7.myplace.com cat /etc/oracle-release /etc/redhat-release
Oracle Linux Server release 7.9
Red Hat Enterprise Linux Server release 7.9 (Maipo)
$ ssh me@myol8.myplace.com cat /etc/oracle-release /etc/redhat-release
Oracle Linux Server release 8.8
Red Hat Enterprise Linux release 8.8 (Ootpa)
$ ssh me@myol9.myplace.com cat /etc/oracle-release /etc/redhat-release
Oracle Linux Server release 9.2
Red Hat Enterprise Linux release 9.2 (Plow)
I guess Oracle doesn't remove all the branding. I don't remember how CentOS handled this.
My understanding is /etc/redhat-release needs to be there because some (dumb) blob drivers specifically check that file to see if you're running a compatible RHEL system before it'll even attempt to install.
At a previous job, we had a wrapper script that swapped the file out before attempting to launch Dell software installers/firmware updaters, because they sometimes checked for hardcoded exact strings like that in there, and errored out, and whether or not it did that varied back and forth over the years.
