Firstly, your hardware must support the power-off operation which means having a suitable PSU and the function suitably enabled in the BIOS.
Secondly, you need an operating system that supports powering off and is configured to allow that.
Thirdly, you need to issue that appropriate command. This is usually the 'init' command with the correct init level (depending on O/S) which for SCO, as far as I remember, is:
# init 0
(means shutdown the O/S)
# init 6
(means reboot the O/S)
# init 5
(means shutdown and power off)
# init n
(means change to runlevel 'n')
So whether it will work or not depends on a number of things. All you can do is try it and see what happens.
shutdown -iLevel and init Level use the level definition from /etc/inittab .
Run the following command to see its mam page (or click to browse the URL): man inittab
Read the following section of the init command man page.
0
Shut the machine down so it is safe to remove the power.
Have the machine remove power if it can. This state can be
executed only from the console.
Note that init 0 should not be used if you have a USB
keyboard attached to the console. During an init 0, the
USB stack gets shut down and the system then waits for a
keyboard keypress interrupt before rebooting. Since USB is
gone, there's no way for a keypress on the USB keyboard to
get serviced, and the system does not respond. If this
occurs, you must either press the hardware reset button or
power cycle the system.
1
Put the system in single-user mode. Unmount all file
systems except the root filesystem. All user processes are
killed except those connected to the console. It is
recommended that this state be executed only from the
console.
2
Put the system in multiuser mode. All multiuser
environment terminal processes and daemons are spawned.
5
Stop the UNIX system and go to the firmware monitor.
6
Stop the UNIX system and reboot to the run-level defined
by the initdefault entry in /etc/inittab.
The above is from the 6.0.0 documentation but is backwards compatible to Xenix.
---------- Post updated at 01:14 PM ---------- Previous update was at 01:09 PM ----------
If you are unable to power down the system, because the cmos does not support it, you may be able to create a workaround using a UPS that you can send a "power off in 5 minutes" command to just prior to shutting down the SCO system.