The poweroff command closes out filesystems, shutdowns the system, and power it off. Because this command immediately stops all processes, it should be run only in single-user mode. If the system is not in runlevel 0 or 6, poweroff calls shutdown -h, then performs a poweroff.
# poweroff [options]
poweroff Command Examples
1. To shutdown the machine:
2. Call reboot or halt and not shutdown, even when shutdown would normally be called. This option is used to force a hard halt or reboot:
# poweroff -f # poweroff --force
3. To instructs the halt command to instead behave as poweroff:
# poweroff -p # poweroff --poweroff
4. Do not shutdown but make an entry into wtmp file:
# poweroff -w # poweroff --wtmp-only
5. Shut down network interfaces before reboot.
# poweroff -i
6. Place hard drives in standby mode before halt or poweroff.
# poweroff -h
7. Suppress writing to /var/log/wtmp.
# poweroff -d
8. Suppress normal call to sync.
# poweroff -n
5. Set to the verbose mode:
# poweroff --verbose