dnf repolist
dnf provides htop or dnf provides */Containerfile
dnf search htop
dnf search all htop
dnf update The same as dnf upgrade. The "update" is an alias for "upgrade".
dnf group install Only mandatory and default packages are installed, to see optional packages use dnf group info and to install with all optional packages do dnf group install --with-optional
dnf group list See group packages that you can install.
dnf group list hidden Some groups are normally only installed through environment groups and not separately, and for that reason don't show when using dnf group list
dnf list installed List installed software on the machine.
dnf history
dnf history info 10
dnf history undo 10
sudo dnf history rollback 10 Let's say you want to undo everything that was installed after number 10. This command seen below would remove mutt, emacs and powertop.
To reinstall something that was removed.
dnf history redo 15
During the exam your virtual machine will not have access to the internet. Hence, we cannot use subscription-manager and associated repos. No repositories will be available by default. This means we cannot install any packages by default.
Red Hat will tell you that a repository is available at a certain location, and you will have to configure the repository for that manually.
You need to be capable of configuring repository access, or you will fail the exam.
This is just and FYI. You will not have access to these repositories during the exam!.
To access repositories that are offered through subscription manager, use dnf config-manager --enable name-of-the-repository to add repository access.
To enable third party repositories, create a repo files in "/etc/yum.repos.d/".
Let's create a local repository from the RHEL 9 ISO file. I mount the RHEL 9 ISO in the virtual cdrom drive. For me, it's mounted on "/run/media/armann/RHEL-9-0-0-BaseOS-x86_64".
If you need to mount the cdrom manually. mount /dev/sr0 /mnt
Let's copy the iso file to our computer. Make sure you have around 9GB available
on the root of your hard disk. dd if=/dev/sr0 of=/rhel9.iso bs=1M status=progress
Let's edit "/etc/fstab" so it's mounted automatically for us. You can see the last line, that's how we mount the rhel9.iso automatically after boot.
Let's mount it. mount -a
Now we need to manually create the repository file.
Go under "/etc/yum.repos.d/".
Create a file, vim baseos.repo
Let's add the following lines into baseos.repo.
[baseos]
name=baseos
baseurl=file:///opt/iso/BaseOS
gpgcheck=0
Create another repo file.
Call it appstream.repo
[appstream]
name=appstream
baseurl=file:///opt/iso/AppStream
gpgcheck=0
Now we can check to see if our repository file is okay.
dnf repolist
We should see baseos and appstream and no errors.
BaseOS repo is for packages that don't change during the lifecycle of the OS. The AppStream repo is for packages that do change major versions during the lifecycle period of the Os.
To see all the software you are entitled to use with the subscription attached to the machine.
rct cat-cert /etc/pki/entitlement/5715597599610761455.pem