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halt(8) [centos man page]

HALT(8) 							       halt								   HALT(8)

NAME
halt, poweroff, reboot - Halt, power-off or reboot the machine SYNOPSIS
halt [OPTIONS...] poweroff [OPTIONS...] reboot [OPTIONS...] DESCRIPTION
halt, poweroff, reboot may be used to halt, power-off or reboot the machine. OPTIONS
The following options are understood: --help Prints a short help text and exits. --halt Halt the machine, regardless of which one of the three commands is invoked. -p, --poweroff Power-off the machine, regardless of which one of the three commands is invoked. --reboot Reboot the machine, regardless of which one of the three commands is invoked. -f, --force Force immediate halt, power-off, reboot. Do not contact the init system. -w, --wtmp-only Only write wtmp shutdown entry, do not actually halt, power-off, reboot. -d, --no-wtmp Do not write wtmp shutdown entry. --no-wall Do not send wall message before halt, power-off, reboot. EXIT STATUS
On success, 0 is returned, a non-zero failure code otherwise. NOTES
These are legacy commands available for compatibility only. SEE ALSO
systemd(1), systemctl(1), shutdown(8), wall(1) systemd 208 HALT(8)

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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 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) Nov 6, 2001 HALT(8)

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