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poweroff Command Cheat Sheet

poweroff sends a signal to the system to bring it down and power off the machine.

Synopsis

poweroff [OPTIONS]

Basic Usage

Shut Down Immediately

sudo poweroff
This is equivalent to systemctl poweroff or shutdown -h now.

Options

Force Power Off (-f)

If the system hangs and won't shut down normally (ignoring regular init), use force.

sudo poweroff -f
Warning: This skips the safe shutdown of services and unmounting of disks. Data loss may occur.

Don't Halt, Just Power Off (-p)

Usually default.

sudo poweroff -p

Reboot Instead (--reboot)

sudo poweroff --reboot
(Why? Just use reboot).

Comparison of Commands

Command Action Technical Details (Systemd)
poweroff Shut down & Power cut Links to systemctl poweroff.
halt Stop OS CPU stops, but power usually remains ON.
reboot Restart Links to systemctl reboot.
shutdown Scheduled Stop Can schedule time & warn users. Safe wrapper.

Best Practice: Use shutdown now or poweroff for immediate turn off. Use shutdown -h +10 for scheduled maintenance.

Notes

  • In modern Systemd systems (Ubuntu, CentOS, Arch), poweroff, reboot, and halt are all symlinks to systemctl.
  • ACPI: Poweroff requires ACPI support in BIOS/Kernel to actually cut the electricity.