09-19-2007
The shutdown command runs various shutdown scripts and then finally invokes the halt command. Not running those scripts could be a problem depending on what they do. As one example, if you are running an Oracle database, you could lose transactions or even mangle the database. The shutdown command can also notify the users that a shutdown is about to happen. So yes you should use the shutdown command rather than halt. But if you tried shutdown and it hung, a halt command is better than simply turning off the power switch because "halt" will at least attempt to sync the disks which is better than nothing.
The shutdown command will only result in the halt command being run if you are halting the system. My feeling is that most shutdown commands are to reboot the system rather than halt it. These wind up invoking "reboot" rather than "halt". And "shutdown" is better than "reboot" for this. Again, you want those shutdown scripts to run.
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=========================================================
Errrr previously post: https://www.unix.com/sco/140055-sco-open-server-6-system-halt.html
Then I think it's better to post here. If I wrong, please ignore.
=========================================================
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LEARN ABOUT REDHAT
reboot
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.
-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 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 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)
Nov 6, 2001 HALT(8)