HALT(8)               Linux System Administrator's Manual              HALT(8)



NAME
       halt, reboot, poweroff - stop the system.

SYNOPSIS
       /sbin/halt [-n] [-w] [-d] [-f] [-i] [-p] [-h]
       /sbin/reboot [-n] [-w] [-d] [-f] [-i]
       /sbin/poweroff [-n] [-w] [-d] [-f] [-i] [-h]

DESCRIPTION
       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.

OPTIONS
       -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.

DIAGNOSTICS
       If you're not the superuser, you will get the message `must be
       superuser'.

NOTES
       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.

AUTHOR
       Miquel van Smoorenburg, miquels@cistron.nl

SEE ALSO
       shutdown(8), init(8)



                               November 6, 2001                        HALT(8)