halt, reboot, poweroff - stop the system.
/sbin/halt [-n] [-w] [-d] [-f] [-i]
[-p] [-h]
/sbin/reboot [-n] [-w] [-d] [-f] [-i]
/sbin/poweroff [-n] [-w] [-d] [-f]
[-i] [-h]
Halt notes that the system is being brought down in the file
/var/log/wtmp, and then either tells the kernel to halt, reboot or
power-off the system.
If halt or reboot is called when the system is
not in runlevel 0 or 6, in other words when it's
running normally, shutdown will be invoked instead (with the
-h or -r flag). For more info see the shutdown(8)
manpage.
The rest of this manpage describes the behaviour in runlevels 0
and 6, that is when the systems shutdown scripts are being run.
- -n
- Don't sync before reboot or halt. Note that the kernel and storage drivers
may still sync.
- -w
- Don't actually reboot or halt but only write the wtmp record (in the
/var/log/wtmp file).
- -d
- Don't write the wtmp record. The -n flag implies -d.
- -f
- Force halt or reboot, don't call shutdown(8).
- -i
- Shut down all network interfaces just before halt or reboot.
- -h
- Put all hard drives on the system in stand-by mode just before halt or
power-off.
- -p
- When halting the system, switch off the power. This is the default when
halt is called as poweroff.
If you're not the superuser, you will get the message `must be superuser'.
Under older sysvinit releases , reboot and halt should
never be called directly. From release 2.74 on halt and reboot
invoke shutdown(8) if the system is not in runlevel 0 or 6. This means
that if halt or reboot cannot find out the current runlevel (for
example, when /var/run/utmp hasn't been initialized correctly)
shutdown will be called, which might not be what you want. Use the
-f flag if you want to do a hard halt or reboot.
The -h flag puts all hard disks in standby mode just before
halt or power-off. Right now this is only implemented for IDE drives. A side
effect of putting the drive in stand-by mode is that the write cache on the
disk is flushed. This is important for IDE drives, since the kernel doesn't
flush the write cache itself before power-off.
The halt program uses /proc/ide/hd* to find all IDE disk
devices, which means that /proc needs to be mounted when halt
or poweroff is called or the -h switch will do nothing.
Miquel van Smoorenburg, miquels@cistron.nl