How to Check the Kernel Version on Ubuntu | Detailed Steps and Update Guide

By 佐川 直弘 | Naohiro Sagawa (運営者)

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1. Introduction

Ubuntu is one of the most widely used open-source operating systems among Linux distributions. One of the key components that significantly impacts system stability, security, and performance is the “kernel.” The kernel is the core of the OS, serving as the central component that directly communicates between hardware and software, determining the overall behavior of the system. Therefore, checking the kernel version is crucial for Ubuntu users.

Checking the kernel version is especially useful for troubleshooting, security measures, and performance optimization. Since security updates are regularly provided for the kernel, it is recommended to keep track of the latest versions and ensure updates are applied as needed.

This guide provides multiple methods to check the kernel version on Ubuntu. It covers both command-line approaches using the terminal and graphical user interface (GUI) methods. Additionally, we will explain fundamental knowledge about kernel versions and key points to consider.

2. What is a Kernel?

In Ubuntu and other Linux distributions, the “kernel” functions as the core of the system. The kernel is responsible for exchanging information between hardware and software. This section explains the specific role of the kernel and its importance.

Role of the Kernel

The kernel acts as a bridge between hardware and software, performing the following essential functions:

• Resource Management
  The kernel manages system resources such as the CPU, memory, and disk, ensuring that applications use them efficiently. This enables multiple processes to run simultaneously without system slowdowns.
• Device Management
  The kernel controls hardware devices such as printers, keyboards, mice, and network cards, allowing applications to access them. It communicates with hardware via device drivers, handling user input and system output.
• Security and Protection
  The kernel ensures system security by separating user space and kernel space. This prevents regular applications from directly accessing hardware, maintaining system stability and security.

Importance of the Kernel in Ubuntu

Updating the kernel in Ubuntu not only enhances system stability but also improves security. When kernel vulnerabilities are discovered, the Ubuntu development team quickly provides updates, making it crucial to check the kernel version regularly and update it when necessary.

Since the kernel is a fundamental component of the entire system, managing it properly ensures better performance and security. In the next section, we will explain the specific steps to check the kernel version in Ubuntu.

3. How to Check the Kernel Version

There are multiple ways to check the kernel version in Ubuntu. This section introduces easy methods using the terminal, along with explanations of each command and its output.

Checking the Kernel Version with the uname Command

The simplest and most commonly used method is the uname command. This command retrieves system information, including the kernel version.

1. Open the terminal.
2. Enter the following command and press Enter.

   uname -r

• Option -r displays the kernel release version. Example output:

   5.4.0-66-generic

In this output, 5.4.0-66-generic represents the kernel version. The version format includes major, minor, and patch numbers.

Checking with the /proc/version File

Another method is to check the /proc/version file, which contains the current kernel version and compilation details.

1. Run the following command in the terminal.

   cat /proc/version

Example output:

   Linux version 5.4.0-66-generic (buildd@lcy01-amd64-025) (gcc version 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04)) #74-Ubuntu SMP Thu Jan 14 18:28:23 UTC 2021

This output provides not only the kernel version but also details about the compiler version and build date.

Checking with the hostnamectl Command

From Ubuntu 16.04 onwards, you can use the hostnamectl command to check system information, including the kernel version.

1. Run the following command in the terminal.

   hostnamectl

Example output:

   Static hostname: ubuntu
         Icon name: computer-vm
           Chassis: vm
        Machine ID: abcdef1234567890
           Boot ID: 123456abcdef98765
    Operating System: Ubuntu 20.04.1 LTS
              Kernel: Linux 5.4.0-66-generic
        Architecture: x86-64

In this output, the kernel version is displayed next to “Kernel:”.

Comparison of Methods and Their Use Cases

• uname -r: Best for quickly checking only the kernel version.
• /proc/version: Useful when more detailed information is needed.
• hostnamectl: Ideal for checking system-wide information along with the kernel version.

These are the main ways to check the kernel version using the terminal. In the next section, we will cover how to check the kernel version using the GUI.

4. Checking the Kernel Version Using GUI

Ubuntu also allows users to check the kernel version through a graphical user interface (GUI) without using the command line. The GUI method is intuitive and convenient, especially for users unfamiliar with terminal commands.

Using the System Information Tool

Ubuntu provides a “Settings” menu that displays basic system information, including the kernel version. Follow these steps:

1. Open the Settings menu

• Click the system menu (gear icon) in the upper right corner of the desktop and select “Settings.”

1. Open the “About” or “Details” section

• In the settings menu, select “About” or “Details” (the name may vary depending on the Ubuntu version).

1. Check the system information

• In the “About” section, basic system information is displayed, including the kernel version, which can be found under “Kernel” or “Linux version.” Example:

   Linux 5.4.0-66-generic

Advantages of Using GUI

The GUI method is helpful for users who prefer a visual approach to system information. It eliminates the need for command-line input, making it easier for beginners to access system details quickly.

That concludes the explanation of how to check the kernel version using GUI. Next, we will cover “Understanding Kernel Version Numbers and Their Meaning.”

5. Understanding Kernel Version Numbers and Their Meaning

Kernel versions are displayed as numbers like 5.4.0-66-generic. These numbers contain important information about the kernel release and its updates. Understanding the format helps users make informed decisions when updating the kernel.

Kernel Version Format

A typical Linux kernel version follows this format:

   [Major].[Minor].[Patch]-[Build]-[Distribution]

Example: 5.4.0-66-generic

• Major Version (5): Indicates a major update with significant changes and improvements.
• Minor Version (4): Represents incremental updates within the major release.
• Patch Level (0): Small bug fixes and security patches.
• Build Number (66): A specific build number assigned by the distribution.
• Distribution Tag (generic): Shows the type of kernel build (e.g., generic, lowlatency, etc.).

LTS and Non-LTS Kernel Versions

Ubuntu provides two types of kernels:

• LTS (Long Term Support) Kernel: Supported for an extended period, ideal for stable environments.
• Non-LTS Kernel: Receives frequent updates but has a shorter support period.

To check whether you are using an LTS kernel, compare your kernel version with Ubuntu’s official kernel lifecycle table.

6. How to Update the Kernel

Keeping your kernel up to date is crucial for system security and performance. This section explains how to update the Ubuntu kernel safely.

Checking Available Kernel Updates

First, check if a new kernel version is available by running:

   sudo apt update
   sudo apt list --upgradable | grep linux-image

Updating the Kernel Using apt

To update the kernel using the standard package manager:

   sudo apt upgrade linux-image-generic

Then, reboot the system:

   sudo reboot

Manually Installing a Specific Kernel Version

To install a specific kernel version:

   sudo apt install linux-image-5.15.0-60-generic

Replace 5.15.0-60-generic with your desired version.

Checking the Installed Kernel After Update

After rebooting, confirm that the update was applied:

   uname -r

The output should display the new kernel version.

7. Downgrading the Kernel (Reverting to an Older Version)

If an updated kernel causes system instability, you can revert to a previous version.

Booting into an Older Kernel

During startup, press Shift to enter the GRUB menu. Select Advanced options for Ubuntu, then choose an older kernel.

Removing the Problematic Kernel

Once booted into a stable kernel, remove the problematic one:

   sudo apt remove linux-image-5.15.0-60-generic

Then, update GRUB:

   sudo update-grub
   sudo reboot

8. Conclusion

Checking and updating the kernel is an essential part of maintaining a secure and stable Ubuntu system. This guide covered multiple methods for checking the kernel version, including both terminal and GUI approaches. We also explored kernel version structures, update methods, and how to revert to a previous version if needed.

By regularly monitoring and updating your kernel, you can ensure improved security, stability, and performance. Whether you are a beginner or an advanced user, understanding these processes will help you manage your Ubuntu system efficiently.

If you have any questions or need further assistance, feel free to leave a comment below!