Uly.me

cloud engineer

kernel

Check for new kernel

Checking for new kernel on multiple distros.

Redhat, Centos, Fedora, Rocky

rpm -qa kernel
yum list installed kernel

Arch Linux

pacman -Q | grep linux

Fedora

dnf list installed kernel

SUSE

rpm -qa | grep -i kernel
zypper search -i kernel

Debian, Ubuntu, Mint

dpkg --list | grep linux-image

Downgrade Redhat Kernel

How to downgrade a Redhat kernel within the same release.

List kernel.

yum list kernel-3.10.0-862*
yum list kernel-3.10*

Install previous kernel if missing.

yum install kernel-3.10.0-862.el7

Downgrade to next minor release.

yum downgrade redhat-release

Reinstall Kernel

How to reinstall the latest kernel and rebuild initramfs.

Find the latest kernel.

rpm -qa kernel
kernel-3.10.0-1160.6.1.el7.x86_64
kernel-3.10.0-1160.11.1.el7.x86_64

Remove the kernel first, then reinstall.

yum remove kernel-3.10.0-1160.6.1.el7.x86_64
yum install kernel-3.10.0-1160.6.1.el7.x86_64

Removing Old Kernels

How to check which kernel is running on your system

uname -sr

List all kernels installed on the system.

rpm -q kernel

Removing old kernels using package-cleanup. This keeps 2 kernels on the system.

yum install yum-utils
package-cleanup --oldkernels --count=2

Checking Last Patch

You can check when the system was last patch using the following.

# check RPM when the last updates were ran.
rpm -qa --last | grep kernel
# this is a bit of a stretch, but typically a reboot is performed after an upgrade.
uptime