Guide: How to Check Last Reboot Time in Linux – Easy Steps

Are you curious about when your Linux system was last rebooted? Let me show you how to check the last reboot time in Linux using simple commands.

Key Takeaways

• The “last reboot” command displays previous reboot dates and times from the /var/log/wtmp file.
• The “who -b” command shows the last system reboot date and time.
• The “uptime -s” command can be used to view the time of the last reboot.
• Using the “dmesg” command, you can check the last reboot time by searching for the word “systemd” in the kernel ring buffer.
• With these simple commands, you can easily determine the last reboot time of your Linux system.

Using the “last reboot” command

By using the “last reboot” command in Linux, you can easily find the system’s boot time along with other valuable information. This command allows you to access the previous reboot dates and times stored in the /var/log/wtmp file. It provides a comprehensive overview of when your system was last restarted and tracks the duration of each session.

To use the “last reboot” command, simply open your terminal and type “last reboot” followed by the Enter key. The output will display a list of reboot timestamps, including the date, time, and the duration since the system was last restarted.

One alternative way to retrieve the system restart time is by using the “uptime -s” command. This command shows the exact time of the last system reboot. It is a quick and efficient method to check the system’s boot time without the need to access log files. Simply enter “uptime -s” in your terminal, and the output will provide the precise time of the last reboot.

Command	Description
last reboot	Displays previous reboot dates and times from /var/log/wtmp file
uptime -s	Shows the time of the last system reboot

With these simple commands at your disposal, you can easily retrieve the last reboot time of your Linux system. Whether you prefer using the “last reboot” command to access log files or the straightforward “uptime -s” command, you now have the tools to track system performance and troubleshoot any issues with ease.

Using the “who -b” command

The “who -b” command in Linux is a powerful tool that displays the system boot time, allowing you to determine when your system was last restarted. By running this command, you can quickly obtain the exact date and time of the last reboot.

To use the “who -b” command, simply open your terminal and enter the following:

who -b

This command will provide you with the system boot time information, including the date and time of the last system restart. It is a convenient method to check when your Linux system was last rebooted, helping you keep track of system performance and troubleshoot any issues that may arise.

Here is an example output of the “who -b” command:

System Boot Time
Sun Nov 21 10:00:17 2022

Using the “who -b” command simplifies the process of viewing the system boot time in Linux, enabling you to get the information you need quickly and efficiently.

Using the “uptime -s” command

If you want to know the exact time of the last system restart in Linux, the “uptime -s” command is your go-to option. This simple and straightforward command allows you to retrieve the system’s restart time with ease.

To use the “uptime -s” command, open your terminal and type the following:

1

uptime -s

After executing the command, the terminal will display the date and time of the last system reboot. This information can be useful for tracking the system’s performance or troubleshooting any issues that may have occurred.

The “uptime -s” command provides a quick and efficient way to check the last reboot time in Linux without the need for complex commands or extensive system knowledge.

Command	Description
1 uptime -s	Displays the date and time of the last system reboot.

By utilizing the “uptime -s” command in Linux, you can easily access the information you need regarding the last reboot time of your system. This command is a valuable tool for system administrators and users alike, providing essential insights into system performance and troubleshooting potential issues.

Using the “dmesg” command

By utilizing the “dmesg” command in Linux and searching the kernel ring buffer, you can easily determine the last reboot time of your system. This command allows you to access the kernel’s log messages, which contain valuable information about various system events, including reboots.

To check the last reboot time, you need to search for specific keywords in the kernel ring buffer. Typically, the word “systemd” is a good indicator of a reboot event. You can run the following command in your terminal:

dmesg | grep systemd

This command will filter the kernel log messages and display the lines containing the word “systemd.” The line that mentions “systemd” should also include the timestamp of the reboot, allowing you to determine when your system was last restarted.

By analyzing the output of the “dmesg” command, you can easily retrieve the last reboot time and use it as valuable information for system administration, troubleshooting, or monitoring purposes.

Example:

Here is an example output of the “dmesg” command:

[    0.000000] BIOS-provided physical RAM map:

[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009a7ff] usable

[    0.000000] BIOS-e820: [mem 0x000000000009a800-0x000000000009ffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] reserved

[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000007b737fff] usable

[    0.000000] BIOS-e820: [mem 0x000000007b738000-0x000000007b73efff] ACPI data

[    0.000000] BIOS-e820: [mem 0x000000007b73f000-0x000000007b7fffff] ACPI NVS

[    0.000000] BIOS-e820: [mem 0x000000007b800000-0x000000008fffffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000e0000000-0x00000000efffffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000fe000000-0x00000000fe010fff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000fec00000-0x00000000fec00fff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000fed00000-0x00000000fed03fff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000fed1c000-0x00000000fed1ffff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000fee00000-0x00000000fee00fff] reserved

[    0.000000] BIOS-e820: [mem 0x00000000ff000000-0x00000000ffffffff] reserved

[    0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000023fffffff] usable

[    0.000000] NX (Execute Disable) protection: active

In this example, the output does not specifically mention a reboot event or the last reboot time. However, if you search for the keyword “systemd,” you may find relevant log messages that indicate a reboot and provide the associated timestamp.

By utilizing the “dmesg” command and searching the kernel ring buffer, you can easily determine the last reboot time of your Linux system.

Putting it all together

By combining the power of the “last reboot,” “who -b,” “uptime -s,” and “dmesg” commands, you can efficiently check the last reboot time of your Linux system. Let’s summarize the steps:

1. Open your Linux terminal.
2. To use the “last reboot” command, type

   1	last reboot

   and press Enter. This will display the previous reboot dates and times from the

   1	/var/log/wtmp

   file.
3. Alternatively, you can use the “who -b” command by typing

   1

   who -b

   and pressing Enter. This will show you the exact date and time of the last system reboot.

4. If you prefer using the “uptime -s” command, simply type

   1

   uptime -s

   and press Enter. This command will provide you with the time of the last reboot.

5. Another option is to employ the “dmesg” command. Type

   1

   dmesg

   and press Enter to access the kernel ring buffer. Search for the keyword “systemd” to find the relevant information about the last reboot time.

Using these commands, you can easily obtain the last reboot time of your Linux system. It is advisable to note down this information for future reference or troubleshooting purposes.

Example usage:

Command: last reboot

Output: reboot system boot 4.15.0-101-generic Sun Dec 20 16:56 still running

Command: who -b

Output: system boot 2021-12-20 16:56

Command: uptime -s

Output: 2021-12-20 16:56:20

Command: dmesg | grep systemd

Output: [ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-101-generic root=UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx ro quiet splash systemd.show_status=false

By following these steps and utilizing the commands mentioned, you can easily check the last reboot time of your Linux system. Stay informed about your system’s performance and be prepared for any troubleshooting that may arise.

Commands to check last reboot time:

Command	Description
last reboot	Displays previous reboot dates and times from the 1 /var/log/wtmp file
who -b	Shows the exact date and time of the last system reboot
uptime -s	Provides the time of the last reboot
dmesg | grep systemd	Searches the kernel ring buffer for the keyword “systemd” to find the last reboot time

Conclusion

By following the simple steps outlined in this guide, you can confidently check the last reboot time in Linux and gain valuable insights into your system’s performance.

To check the last reboot time in Linux, there are several easy steps you can follow. One method is to use the “last reboot” command, which displays the previous reboot dates and times from the /var/log/wtmp file. This command provides a convenient way to retrieve the essential information about your system’s restart time.

Another option is to use the “who -b” command, which shows the last system reboot date and time. This command gives you specific details about the last reboot, displaying the exact date and time for your reference.

The “uptime -s” command can also be used to view the time of the last reboot. This command provides a quick way to retrieve the system’s restart time without any complications. Simply run this command, and you will have the necessary information at your fingertips.

Additionally, the “dmesg” command can be used to check the last reboot time by searching for the word “systemd” in the kernel ring buffer. This command allows you to explore the kernel ring buffer and locate the relevant information about the system’s last reboot.

By using these simple commands, you can easily determine the last reboot time of your Linux system. This knowledge is crucial for system administrators and users who want to track system performance and troubleshoot issues effectively. Armed with this information, you’ll be better equipped to understand your system’s behavior and make informed decisions.