Linux service manager used by Raspberry Pi OS to start and supervise background services.
software
Knowledge about systemd
Let a frozen Raspberry Pi reboot itself: the hardware watchdog via systemd (max 15 s)procedure · unverified · Remote Pis occasionally hang. systemd can drive the built-in hardware watchdog with RuntimeWatchdogSec in /etc/systemd/system.conf, with no extra daemon. The bcm2835 watchdog can't time out after more than 15 seconds, so keep the value at or below that.
Shut down a headless Raspberry Pi safely: a button instead of pulling the plugprocedure · unverified · Pulling the power risks SD card and file system damage. Give headless devices a shutdown button: the onboard power button (or J2 pads) on Pi 5, the gpio-shutdown overlay on earlier models. The default GPIO3 button also powers the board back on, but GPIO3 is the I2C clock pin.