I'm using CachyOS with KDE, and whenever I run `pacman -Syu` or update through the graphical software manager, I get a notification saying that a reboot is required. I thought Linux generally didn't need reboots after updates. What does the notification actually mean, and when do I really need to restart?
4 Answers
Most ordinary applications can be updated while the system is running. Programs that were already open may continue using the old code until they’re restarted, and services may need to be restarted too. Kernel updates, systemd updates, graphics drivers, VPN software, and some other low-level drivers are the cases where a full reboot is generally the simplest and safest option.
Since CachyOS is Arch-based and uses relatively current packages, kernel updates may appear fairly often. You can postpone them, but make sure you eventually reboot into the updated kernel. If you need maximum uptime, techniques such as kernel live patching exist, though they’re mostly useful for servers and are considerably more complicated than simply rebooting.
The notification usually means that an update installed a new kernel or some low-level component. Your system can keep running on the old kernel that was loaded at boot, but the new one won’t be used until you restart. It’s advice rather than a forced reboot—you can keep working and reboot later when convenient.
Linux doesn’t promise that reboots are never needed. The main difference is that the system normally won’t force you to restart immediately or interrupt your work to finish installing updates. You can postpone the reboot, but you’ll keep using the old kernel and some old libraries or services until you restart them.
Browsers and desktop applications can sometimes behave strangely after updates, but usually restarting just that application is enough. You don’t necessarily need to reboot the entire machine.