HALTSection: Linux System Administrator's Manual (8)
Updated: Nov 6, 2001
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NAMEhalt, 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]
DESCRIPTIONHalt 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.
DIAGNOSTICSIf you're not the superuser, you will get the message `must be superuser'.
NOTESUnder 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.
AUTHORMiquel van Smoorenburg, firstname.lastname@example.org
SEE ALSOshutdown(8), init(8)
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Time: 01:47:14 GMT, July 08, 2020