Quick commands to find the last system boot time and why it matters. 16.11.2025 | reading time: 2 min You opened a shell and need to know when the machine was last started; this short guide shows practical commands to tell the last system boot time and what to check next. Quick demonstration Try these commands on the machine you are investigating to see the boot time and recent reboots: ```$ who -b system boot 2025-11-16 09:22 $ uptime -s 2025-11-16 09:22:07 $ last reboot -n 3 reboot system boot 5.11.0-37-generic Mon Nov 16 09:22 still running reboot system boot 5.11.0-37-generic Sun Nov 15 22:10 - 09:22 (11+11:12)``` Edge cases to watch Note that timezone differences change the human-readable timestamp, containers show the host boot differently, suspend/resume does not reset the boot time, and virtual machines may report the hypervisor's boot time instead of the guest's; when in doubt inspect `/proc/uptime` for seconds since boot and `/proc/stat` for the "btime" field. Other commands to try If the system uses systemd, `systemd-analyze` reports kernel and userspace timings and `journalctl --list-boots` lists recorded boots; `journalctl -b` shows logs since the last boot and `last -x` reveals shutdowns and runlevel changes for deeper context. Wrap-up and next steps You now have fast, reliable ways to answer the simple question "when did this system boot?" and a few follow-up checks to investigate problems that happened after that boot; continue practicing these commands and consider formal study to deepen your Linux skills with courses and certifications like CompTIA Linux+ or LPIC-1 and intensive exam preparation at bitsandbytes.academy. Join Bits & Bytes Academy First class LINUX exam preparation. boot-process utilities troubleshooting processes
