poweroff
Shut down the computer
TLDR
Power off the system
Halt the system (same as halt)
Reboot the system (same as reboot)
Shut down immediately without contacting the system manager
Write the wtmp shutdown entry without shutting down the system
SYNOPSIS
poweroff [options]
PARAMETERS
--help
Displays a help message and exits.--version
Displays version information and exits.--halt
Halt the machine. (Equivalent to running halt
).--reboot
Reboot the machine after shutdown.--force
Forces immediate shutdown (bypasses the init system). Use with caution!
DESCRIPTION
The poweroff
command is used to halt the system and then turn off the power. It's essentially a system shutdown procedure that goes a step further by cutting off the power supply, if the hardware supports it.
By default, poweroff
performs a clean shutdown by sending a signal to all processes, unmounting file systems, and stopping all services. It prevents data loss and ensures the system is in a consistent state before powering down.
Often poweroff
is a symbolic link to shutdown
or systemctl poweroff
, inheriting its behavior and arguments. Therefore, the exact actions performed during a poweroff may vary slightly depending on the system's init system (e.g., systemd, SysVinit).
CAVEATS
Using the --force
option can lead to data corruption if the system is not in a consistent state. It is generally recommended to avoid this option unless the system is completely unresponsive.
The actual power-off functionality depends on the hardware and BIOS support. Some systems may only halt instead of fully powering off.
EXIT STATUS
The poweroff
command returns 0 on success and a non-zero value on failure.
SECURITY CONSIDERATIONS
poweroff
usually requires root privileges. Allowing regular users to execute this command directly can pose a security risk.
HISTORY
The poweroff
command has existed in Unix-like systems for a long time, dating back to the early days of Unix.
Its primary purpose has always been to provide a simple and standardized way to shut down the system and turn off the power.
The specific implementation and features have evolved over time, especially with the introduction of different init systems like System V init and systemd.