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 behavior 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. This implies -d.
- -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.
- -f
- Force halt or reboot, don't call shutdown(8).
- -i
- Shut down all network interfaces just before halt or
reboot. Warning: This may not work on interfaces which do not have
an IP address and should ideally be handled by a network manager
service.
- -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 and
/var/run/runlevel does not exist)
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
shutdown(8),
init(8)