CentOS/RHEL: removing old kernels

These are short historical notes on removing old kernels to reclaim limited disk space, for example on VPS instances and laptops. The example keeps two kernels; adjust the count if you intend to retain more or fewer.

List installed kernels

List the installed RHEL kernel packages:

$ rpm -qa kernel\* |sort -V
kernel-4.18.0-240.10.1.el8_3.x86_64
kernel-4.18.9-200.el8_3.x86_64
kernel-4.18.10-200.el8_3.x86_64
kernel-core-4.18.0-240.10.1.el8_3.x86_64
kernel-core-4.18.9-200.el8_3.x86_64
kernel-core-4.18.10-200.el8_3.x86_64
kernel-devel-4.18.0-240.10.1.el8_3.x86_64
kernel-devel-4.18.9-200.el8_3.x86_64
kernel-devel-4.18.10-200.el8_3.x86_64
kernel-headers-4.18.0-240.10.1.el8_3.x86_64
kernel-modules-4.18.0-240.10.1.el8_3.x86_64
kernel-modules-4.18.9-200.el8_3.x86_64
kernel-modules-4.18.10-200.el8_3.x86_64
kernel-modules-extra-4.18.9-200.el8_3.x86_64
kernel-modules-extra-4.18.10-200.el8_3.x86_64
kernel-tools-4.18.0-240.10.1.el8_3.x86_64
kernel-tools-libs-4.18.0-240.10.1.el8_3.x86_64

Remove installed kernels

Fedora 28 and later; RHEL/CentOS 8 and later

$ dnf remove $(dnf repoquery --installonly --latest-limit=-2 -q)

Fedora 27 and earlier; RHEL/CentOS 6–7 and earlier

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

Limit the number of retained kernels

Set installonly_limit in /etc/yum.conf or /etc/dnf/dnf.conf:

echo "installonly_limit=2" >> /etc/yum.conf