Linux list all kernels

List Or Check All Installed Linux Kernels From Commandline

Linux Kernel is the core component of a GNU/Linux operating system. It is a free, opensource, monolithic, modular, multitasking, Unix-like operating system kernel. It is created by Linus Torvalds for his i386 PC in 1991. We can install more than one Kernel in our system. Ever wondered how many Linux Kernels you have installed in your Linux box? No? Well, this brief tutorial will teach you how to view or check all installed Linux Kernels along with their versions from commandline in different Linux operating systems.

Check All Installed Linux Kernels From Commandline

Depending upon the Linux distribution you use, there are multiple ways to check all installed Linux kernel details in your system. The easiest and quickest way to check all installed Kernels in a Linux is by using find command.

By default, all installed Linux Kernels and their associated files are stored under /boot directory. Simply check the contents of this directory using find command to view the list of installed Kernels:

Sample output from my Ubuntu 20.04 LTS desktop:

As you see in the above output, there are two Linux Kernels versions (5.4.0-64 and 5.4.0-65) are installed in my Ubuntu desktop machine.

Now we will see distribution-specific methods to find out installed Linux kernel details. First, let us start from Alpine Linux.

1. Check installed Kernels in Alpine Linux

We can check all installed Kernels along with their versions using the following apk command:

Sample output:

2. List installed Kernels in Arch Linux

To view all installed in Arch Linux and its variants like Manjaro Linux, run the following pacman command:

Sample output:

You can also combine pacman and grep commands to list installed Kernel versions:

Sample output:

As you can see, I have only one Linux Kernel in my Arch Linux system and its version is 5.9.14.

3. Find installed Linux Kernels in Debian, Ubuntu, Pop!_OS

In Debian and other Debian-based systems like Ubuntu, Pop!_OS, Linux Mint, we can find the list of all installed Kernels using dpkg command:

Sample output:

4. View installed Kernels in Fedora, CentOS, RHEL, AlmaLinux

In RPM-based systems such as Fedora and its downstream versions such as CentOS, RHEL and RHEL-clones such as AlmaLinux, we can view all installed Kernels using rpm command like below:

Sample output from Fedora 33:

Sample output from AlmaLinux 8.3:

5. List all installed Linux Kernels in openSUSE

Since openSUSE is also a RPM-based system, the command to list all installed Linux Kernels is same as Fedora, RHEL distributions.

Bonus tip — View only current Kernel details

To view the currently running Kernel, run:

You know now the list of installed Kernels on your Linux system. How would you find when a specific Linux Kernel version is last booted? That’s easy! Refer the following guide to check when a Linux kernel last used or booted on.

Hope this helps.

Related read:

Senthilkumar Palani (aka SK) is the Founder and Editor in chief of OSTechNix. He is a Linux/Unix enthusiast and FOSS supporter. He lives in Tamilnadu, India.

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List Or Check All Installed Linux Kernels From Commandline

Linux Kernel is the core component of a GNU/Linux operating system. It is a free, opensource, monolithic, modular, multitasking, Unix-like operating system kernel. It is created by Linus Torvalds for his i386 PC in 1991. We can install more than one Kernel in our system. Ever wondered how many Linux Kernels you have installed in your Linux box? No? Well, this brief tutorial will teach you how to view or check all installed Linux Kernels along with their versions from commandline in different Linux operating systems.

Check All Installed Linux Kernels From Commandline

Depending upon the Linux distribution you use, there are multiple ways to check all installed Linux kernel details in your system. The easiest and quickest way to check all installed Kernels in a Linux is by using find command.

By default, all installed Linux Kernels and their associated files are stored under /boot directory. Simply check the contents of this directory using find command to view the list of installed Kernels:

Sample output from my Ubuntu 20.04 LTS desktop:

As you see in the above output, there are two Linux Kernels versions (5.4.0-64 and 5.4.0-65) are installed in my Ubuntu desktop machine.

Now we will see distribution-specific methods to find out installed Linux kernel details. First, let us start from Alpine Linux.

1. Check installed Kernels in Alpine Linux

We can check all installed Kernels along with their versions using the following apk command:

Sample output:

2. List installed Kernels in Arch Linux

To view all installed in Arch Linux and its variants like Manjaro Linux, run the following pacman command:

Sample output:

You can also combine pacman and grep commands to list installed Kernel versions:

Sample output:

As you can see, I have only one Linux Kernel in my Arch Linux system and its version is 5.9.14.

3. Find installed Linux Kernels in Debian, Ubuntu, Pop!_OS

In Debian and other Debian-based systems like Ubuntu, Pop!_OS, Linux Mint, we can find the list of all installed Kernels using dpkg command:

Sample output:

4. View installed Kernels in Fedora, CentOS, RHEL, AlmaLinux

In RPM-based systems such as Fedora and its downstream versions such as CentOS, RHEL and RHEL-clones such as AlmaLinux, we can view all installed Kernels using rpm command like below:

Sample output from Fedora 33:

Sample output from AlmaLinux 8.3:

5. List all installed Linux Kernels in openSUSE

Since openSUSE is also a RPM-based system, the command to list all installed Linux Kernels is same as Fedora, RHEL distributions.

Bonus tip – View only current Kernel details

To view the currently running Kernel, run:

You know now the list of installed Kernels on your Linux system. How would you find when a specific Linux Kernel version is last booted? That’s easy! Refer the following guide to check when a Linux kernel last used or booted on.

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Find When A Specific Linux Kernel Version Is Last Booted

You should have installed or upgraded to many new Kernel versions over the time in your Linux machine. If you have multiple Linux Kernels installed on your system, how would you find when a specific Linux Kernel version is last booted? That’s what we are going to find out now. This guide explains how to check when a Linux kernel last used or booted on.

List all installed Linux Kernels

Before we find out when a specific Linux Kernel is booted on, let us check the list of all installed Kernels in our Linux system.

By default, all installed Linux Kernels and their associated files are stored under /boot directory. Simply check the contents of this directory using find command to view the list of installed Kernels:

Sample output from my Ubuntu 20.04 LTS desktop:

As you see in the above output, there are two Linux Kernels versions (5.4.0-64 and 5.4.0-65) are installed. By default, the latest Kernel will boot, so the last access time of the 5.4.0-65 is today. Now let us check when the older Kernel version i.e. 5.4.0-64 is last booted.

Find when a specific Linux Kernel version is last booted

We can easily find when a Kernel is last booted by viewing the last access time of the relevant Kernel image file. In Linux, there is a command line utility named stat that helps us to find such detail.

The stat command is used to display file and filesystem information such as size, permissions, creation and access dates among others.

To find out when a specific Linux Kernel version (E.g. vmlinuz-5.4.0-64-generic ) is last booted, run:

• -c flag is used to specify FORMAT,
• %x is used display the time of last access in human-readable format.

Sample output:

As per the above output, the Linux Kernel version 5.4.0-64 was last booted on January 23, 2021.

You can also use capital %X flag in the above command if you want to display Unix epoch time in the output.

The another way to find the access time of a Linux Kernel is to use find command like below:

Display when a specific Linux Kernel version is last booted using journalctl command

In modern Linux distributions that uses Systemd service manager, we can use journalctl command to display when a Linux kernel is last used or booted on.

To view the most recent boot, run this command:

Sample output:

To list all available previous boots, run:

You will see a long list of previous boots as shown in the below output:

You can now check each boot descriptor to find when a specific Kernel version is last used.

Example:

Sample output:

Hope this helps.

Senthilkumar Palani (aka SK) is the Founder and Editor in chief of OSTechNix. He is a Linux/Unix enthusiast and FOSS supporter. He lives in Tamilnadu, India.

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List all kernels available to install under Ubuntu

Here is the fast command to see which Linux kernels are available to install from the Ubuntu package management system:

Always update to download the latest metadata files for the available packages and the list with a pattern. In our case we want the Ubuntu kernels and they start with “linux-“, before it was easy linux-image-*, but now there are two types of kernels:

1. Signed Linux kernel with name starting “linux-signed-image-” (and alias is “linux-image-“) – “Signed with the Ubuntu EFI key”, which means you should have UEFI BIOS and unsigned (with two words – “more security”)
2. Good old kernel format (so no signing) with name starting “linux-image-unsigned-” – to be sure you pull the unsigned version

And you can use:

to see the kernels available and their descriptions.

Here are the output of the above list command as of the date of writing the article:

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The Linux Kernel Archives

There are several main categories into which kernel releases may fall:

Prepatch Prepatch or «RC» kernels are mainline kernel pre-releases that are mostly aimed at other kernel developers and Linux enthusiasts. They must be compiled from source and usually contain new features that must be tested before they can be put into a stable release. Prepatch kernels are maintained and released by Linus Torvalds. Mainline Mainline tree is maintained by Linus Torvalds. It’s the tree where all new features are introduced and where all the exciting new development happens. New mainline kernels are released every 9-10 weeks. Stable After each mainline kernel is released, it is considered «stable.» Any bug fixes for a stable kernel are backported from the mainline tree and applied by a designated stable kernel maintainer. There are usually only a few bugfix kernel releases until next mainline kernel becomes available — unless it is designated a «longterm maintenance kernel.» Stable kernel updates are released on as-needed basis, usually once a week. Longterm There are usually several «longterm maintenance» kernel releases provided for the purposes of backporting bugfixes for older kernel trees. Only important bugfixes are applied to such kernels and they don’t usually see very frequent releases, especially for older trees.

Longterm release kernels

Version	Maintainer	Released	Projected EOL
5.15	Greg Kroah-Hartman & Sasha Levin	2021-10-31	Oct, 2023
5.10	Greg Kroah-Hartman & Sasha Levin	2020-12-13	Dec, 2026
5.4	Greg Kroah-Hartman & Sasha Levin	2019-11-24	Dec, 2025
4.19	Greg Kroah-Hartman & Sasha Levin	2018-10-22	Dec, 2024
4.14	Greg Kroah-Hartman & Sasha Levin	2017-11-12	Jan, 2024
4.9	Greg Kroah-Hartman & Sasha Levin	2016-12-11	Jan, 2023

Distribution kernels

Many Linux distributions provide their own «longterm maintenance» kernels that may or may not be based on those maintained by kernel developers. These kernel releases are not hosted at kernel.org and kernel developers can provide no support for them.

It is easy to tell if you are running a distribution kernel. Unless you downloaded, compiled and installed your own version of kernel from kernel.org, you are running a distribution kernel. To find out the version of your kernel, run uname -r :

If you see anything at all after the dash, you are running a distribution kernel. Please use the support channels offered by your distribution vendor to obtain kernel support.

Releases FAQ

Here are some questions we routinely receive about kernel release versions. See also the main «FAQ» section for some other topics.

When is the next mainline kernel version going to be released?

Linux kernel follows a simple release cadence:

• after each mainline release, there is a 2-week «merge window» period during which new major features are introduced into the kernel
• after the merge window closes, there is a is a 7-week bugfix and stabilization period with weekly «release candidate» snapshots
• rc7 is usually the last release candidate, though occasionally there may be additional rc8+ releases if that is deemed necessary

So, to find the approximate date of the next mainline kernel release, take the date of the previous mainline release and add 9-10 weeks.

What is the next longterm release going to be?

Longterm kernels are picked based on various factors — major new features, popular commercial distribution needs, device manufacturer demand, maintainer workload and availability, etc. You can roughly estimate when the new longterm version will become available based on how much time has elapsed since the last longterm version was chosen.

Why are some longterm versions supported longer than others?

The «projected EOL» dates are not set in stone. Each new longterm kernel usually starts with only a 2-year projected EOL that can be extended further if there is enough interest from the industry at large to help support it for a longer period of time.

Does the major version number (4.x vs 5.x) mean anything?

No. The major version number is incremented when the number after the dot starts looking «too big.» There is literally no other reason.

Does the odd-even number still mean anything?

A long time ago Linux used a system where odd numbers after the first dot indicated pre-release, development kernels (e.g. 2.1, 2.3, 2.5). This scheme was abandoned after the release of kernel 2.6 and these days pre-release kernels are indicated with «-rc».

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