How to Use the dmesg Command on Linux – How-To Geek

The dmesg command on Linux is used to display the kernel ring buffer, which contains messages related to the Linux kernel and its interactions with hardware devices and drivers. It can be helpful for troubleshooting hardware-related issues and viewing system-level events. Here’s how to use the dmesg command:

Open a Terminal: First, open a terminal on your Linux system. You can typically find the terminal application in the Applications menu or by using a keyboard shortcut like Ctrl + Alt + T.

Run the dmesg Command: In the terminal, simply type the following command and press Enter:

View Kernel Messages: The dmesg command will display a list of kernel messages, starting from the most recent ones. These messages provide information about various events, such as device detection, driver loading, hardware errors, and other kernel-related activities.

Scroll Through Messages: If the output of dmesg is too long to fit in one terminal screen, you can scroll through the messages using the arrow keys or the Page Up and Page Down keys.

Filter dmesg Output (Optional): You can use various options to filter the dmesg output. For example:

• To view only the last 20 lines of the dmesg output, use: dmesg | tail -n 20
• To search for specific keywords in the dmesg output, use: dmesg | grep "keyword"

Clear Kernel Ring Buffer (Optional): By default, the kernel ring buffer accumulates messages from previous system boots. If you want to clear the buffer and only view messages from the current boot, use the -c option: dmesg -c

Please note that the dmesg command typically requires root or superuser privileges to display certain system information. If you encounter an error message or have limited access, try running the command with sudo: sudo dmesg.

Using the dmesg command can be helpful when diagnosing hardware issues, detecting device problems, or understanding the system’s interactions with various components. However, as it shows low-level kernel information, it may not always be directly relevant to general system usage. It’s best to use dmesg in combination with other troubleshooting tools and techniques when investigating specific system or hardware-related problems.