List or Check Installed Linux Kernels using command line

List or Check Installed Linux Kernels

The command varies from one Linux distribution to another. In other words, you need to type the command as per your Linux distro.

RedHat / CentOS / RHEL / Fedora Linux user

You need to use standard rpm command or yum command to list installed software. Type the following command at shell prompt:
$ rpm -qa kernel
Sample Outputs:

kernel-2.6.18-4.1.15.el5
kernel-2.6.18-8.1.14.el5
kernel-2.6.18-8.1.10.el5

Here is another outputs from RHEL 8 server:

kernel-4.18.0-80.7.2.el8_0.x86_64
kernel-4.18.0-80.4.2.el8_0.x86_64

One can run the yum command/dnf command as follows:
yum list installed kernel
OR
dnf list installed kernel

Listing installed kernels on RHEL 8

To list / display current running kernel version

Type the following uname command:
$ uname -r
$ uname -mrs
Sample outputs:

Linux 2.6.18-8.1.14.el5 x86_64

Another outputs from my Ubuntu Linux 18.04 LTS desktop

uname -r
4.18.0-25-generic

Find installed kernel version for Debian / Ubuntu / Pop!_OS Linux

Use the dpkg command along with the grep command to list all installed kernel on your Debian or Ubuntu Linux, enter:
$ dpkg --list | grep linux-image
Sample outputs:

ii  linux-image-2.6.20-15-generic        2.6.20-15.27                           Linux kernel image for version 2.6.20 on x86/
ii  linux-image-2.6.20-16-generic        2.6.20-16.32                           Linux kernel image for version 2.6.20 on x86/
ii  linux-image-generic                  2.6.20.16.28.1                         Generic Linux kernel image

Let us see outputs from my Ubuntu Linux 18.04 LTS desktop:

Arch Linux user

Run the pacman command as follows:
pacman -Q | grep linux

SUSE Enterprise Linux or openSUSE Linux user

Execute the following rpm command:
rpm -qa | grep -i kernel
From my OpenSUSE 15.2 server:

kernel-default-5.3.18-lp152.63.1.x86_64
kernel-default-5.3.18-lp152.60.1.x86_64
kernel-firmware-20200107-lp152.2.3.1.noarch
purge-kernels-service-0-lp152.4.1.noarch

How do I find manually compiled and installed kernels that aren’t in the package manager?

Try to locate them in /lib/modules/ directory using the ls command:
ls -l /lib/modules/

total 12
drwxr-xr-x 5 root root 4096 Jul 29 17:53 4.15.0-55-generic
drwxr-xr-x 5 root root 4096 Jul 29 22:05 4.18.0-25-generic
drwxr-xr-x 5 root root 4096 Aug  1 17:19 5.0.0-23-generic

Alpine Linux user

Run the apk command:
# apk info -vvv | grep -E 'Linux' | grep -iE 'lts|virt'
And we will see:

linux-virt-5.4.84-r0 - Linux lts kernel

How do I list custom compiled kernel?

Use the following find command:
sudo find /boot/ -iname "vmlinuz*"
Here is what I see:

[sudo] password for vivek: 
/boot/vmlinuz-5.4.0-65-generic
/boot/vmlinuz-5.4.0-66-generic
/boot/vmlinuz-5.4.0-25-generic

Please note that vmlinuz is the name of the Linux kernel executable. Typically stored in /boot/ directory. The vmlinuz is a compressed Linux kernel file. It is a bootable file for loading the Linux operating system into memory. On some older Linux distros including latest one, you may find another file called vmlinux. It also the kernel file but in a non-compressed and non-bootable format. To list files in /boot/ run the ls command:
ls -l /boot/
The Linux kernel is compiled by issuing the following command:
sudo make install
The kernel binary on the original UNIX operating system was called unix. When a new Unix kernel containing support for virtual memory was finally written at the University of California at Berkeley, the kernel binary was called vmunix. Hence, the Linux kernel binary is also known as vmlinuz.

Conclusion

You learned how to list installed Kernels version using a bash shell prompt. See how to compile Linux kernel for more information or visit official Linux kernel website here.