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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
       poweroff 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 stor-
	      age 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	harddrives  on	the system in standby mode just before
	      halt or poweroff.

       -p     When halting the system, do a poweroff. This is the default when
	      halt is called as poweroff.

DIAGNOSTICS
       If  you're  not	the superuser, you will get the message 'must be supe-
       ruser'.	Users logged in locally on the console can call halt,  reboot,
       and  poweroff  without  supplying the root password, due to pam_console
       (8).

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 harddisks in standby  mode	just  before  halt  or
       poweroff.  Right	 now  this  is only implemented for IDE drives. A side
       effect of putting the drive in standby 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 poweroff.

       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), pam_console(8)



				  Nov 6, 2001			       HALT(8)
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