3 Ways to Find Kernel Version on Raspberry Pi

The kernel is the core component of a Linux operating system that manages system resources, hardware interfaces, and security. Knowing the kernel version running on your Raspberry Pi allows you to ensure you have the latest security updates and features. Here are three easy methods to find the kernel version on Raspberry Pi.

1. Using the uname Command

The uname command in Linux prints detailed system information, including the kernel version. To find just the kernel release number, use:

uname -r

For example, on my Raspberry Pi running Raspberry Pi OS, this outputs:

5.15.84-v7+

This shows my Pi is running kernel version 5.15.84, built specifically for ARMv7 devices like the Pi.

The uname command has other useful options too:

• uname -a – prints all system information
• uname -s – prints just the kernel name
• uname -n – prints the network node hostname
• uname -p – prints the processor architecture

So uname is handy for checking all kinds of system details.

2. Reading the /proc/version File

The Linux kernel exposes details about itself in the /proc virtual filesystem. Specifically the /proc/version file contains kernel version information.

Use cat to print the contents of this file:

cat /proc/version

Output:

Linux version 5.15.84-v7+ (dom@buildbot) (gcc version 10.2.1 20210110 (release) [ARM/embedded-7-branch revision 415120] (GNU Arm Embedded Toolchain 10.2-2021.01)) #1 Mon Dec 5 11:34:03 GMT 2022

This shows the full kernel release string, compiler version used to build the kernel, and exact build date/time.

So /proc/version offers more verbose kernel details compared to the uname output.

3. Checking dmesg Output

The dmesg command prints the kernel ring buffer – the kernel log buffer containing various system messages and events.

At boot up the kernel prints its version string to this buffer. So dmesg will display the kernel version along with other system initialization info:

dmesg

Searching through the full output you will find lines like:

[    0.000000] Linux version 5.15.84-v7+ (dom@buildbot) (gcc version 10.2.1 20210110 (release) [ARM/embedded-7-branch revision 415120] (GNU Arm Embedded Toolchain 10.2-2021.01)) #1 Mon Dec 5 11:34:03 GMT 2022

To filter the output specifically for kernel version, you can pipe to grep:

dmesg | grep "Linux version"

This prints just kernel version lines.

So dmesg shows lots of system diagnostic info including the kernel version string.

Keeping the Kernel Up-to-Date

Once you have checked the running kernel version on your Pi, you will want to keep it up-to-date for the latest security patches and hardware support.

Raspberry Pi OS includes a simple rpi-update script to fetches the recent kernel from the Raspberry Pi GitHub repo and installs it.

To update to the latest kernel:

sudo rpi-update

After it finishes, reboot and check uname -r to confirm you are running the new version.

I recommend updating the kernel anytime new updates are released – usually every 2-4 weeks. Keeping the kernel current is easy with the rpi-update tool.

Comparing Kernel Versions

When checking kernel versions, you may want to compare release numbers – for example to see if a new update is indeed newer.

The Linux kernel uses the following version numbering scheme:

X.Y.Z

• X – Major release number
• Y – Minor release number
• Z – Patch number

So for example in the 5.15.84 version:

• 5 – Major release number
• 15 – Minor release
• 84 – Patch number

Higher major/minor numbers indicate a newer release. If just the patch number is larger, it represents a small bugfix update.

You can compare versions using these number components. 5.16 would be newer than 5.15, for example. And 5.15.90 is a slightly updated patch release from 5.15.84.

Kernel Version History on the Pi

Here is a history of the key Linux kernel releases used through Raspberry Pi history:

• Linux kernel 2.6 – Initial kernel used from models A, B to early Pi 2‘s. Supported only ARMv6 architecture. Lacks modern kernel features.
• Linux kernel 3.10 to 3.18 – Introduced on later Pi 2 models, and used through the Pi 3 generation. Added ARMv7 and hardware support improvements.
• Linux kernel 4.9 – Debuted on the Pi 3 Model B+ in 2018. Focused on performance optimizations on ARM platforms. Used through 2019 across models.
• Linux kernel 5.4 – Launched in 2020 with the arrival of the Raspberry Pi 4 Model B, 64-bit kernel with improved file system and scheduler performance. Used for 2 years across devices.
• Linux kernel 5.15 – Current kernel bringing further optimizations and support for new Raspberry Pi hardware capabilities. Will likely see updates throughout 2023.

So the Pi ecosystem continually updates the Linux kernel to leverage new features and better hardware support. Updating to latest kernel ensures best performance, compatibility and security hardening on your Raspberry Pi projects.

Conclusion

It‘s valuable to check which Linux kernel version is running on your Raspberry Pi systems. Up-to-date kernels fixes bugs, improves performance and adds support for new boards.

This article covered several handy commands to fetch the kernel release string:

• uname -r – simple kernel version
• cat /proc/version – verbose full version details
• dmesg – grep through kernel boot messages

I recommend running sudo rpi-update periodically to upgrade your Pi to the latest Raspberry Pi OS kernel release. Keeping a current kernel ensures optimal security, stability and hardware support.