To shut down a running &debian-gnu; system, you must not reboot with the reset switch on the front or back of your computer, or just turn off the computer. &debian-gnu; should be shut down in a controlled manner, otherwise files might get lost and/or disk damage might occur. If you run a desktop environment, there is usually an option to log out available from the application menu that allows you to shutdown (or reboot) the system. Alternatively you can press the key combination Ctrl Alt Del or Control Shift Power on Macintosh systems. If the key combinations do not work, a last option is to log in as root and type the necessary commands. Use reboot to reboot the system. Use halt to halt the system without powering it off Under the SysV init system halt had the same effect as poweroff, but with systemd as init system (the default since jessie) their effects are different. . To power off the machine, use poweroff or shutdown -h now. The systemd init system provides additional commands that perform the same functions; for example systemctl reboot or systemctl poweroff.