Which command can be used to reboot the system?

• A. systemctl reboot
• B. reboot
• C. shutdown -r
• D. init 6

Answer: (A)

On systems that use systemd, rebooting should go through the service manager so all services can shut down cleanly and the system can restart in a controlled way. systemctl reboot is the direct, standard way to do this. It asks systemd to perform the full shutdown sequence, which stops services in the proper order, syncs filesystems, and then starts the reboot. This approach is reliable and consistent across modern Linux distributions that rely on systemd.

Other reboot methods exist, but they don’t always guarantee the same clean shutdown behavior on systemd systems. For example, some older or more direct commands may bypass parts of the shutdown process or rely on legacy init behavior, which can lead to incomplete stops of services or unsynced filesystems. That’s why using the systemd interface is the preferred method for rebooting.