SCO Unix, Xenix and ODT General FAQ
This article is from a FAQ concerning SCO operating
systems. While some of the information may be applicable to any OS,
or any Unix or Linux OS, it may be specific to SCO Xenix, Open
There is lots of Linux, Mac OS X and general Unix info elsewhere on
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Yes. haltsys and reboot are both the same file. In some versions, they are a binary, but rest assured that they do sync().
In other versions, they are a shell script and you can look at them
to determine that they do call /bin/sync.
If it's at all possible to use shutdown
to shut the system down, rather than using haltsys or reboot, do
so. shutdown is the proper way to do it; it goes out and kills
processes and attempts to shut the system down as cleanly as
possible. haltsys and reboot, on the other hand, try to shut the
system down as quickly as possible, and any programs which are
running will be rudely interrupted.
Also, if you're using a caching hard drive controller, be aware
that it may not realize the system has been shut down, so even
though Xenix or Unix tells you it's *** Safe to power down ***,
there may still be data left in the hardware cache that isn't
flushed to disk yet. A good, but not foolproof, precaution
is to press a key to allow the system to reboot, and not power down
until the Boot: prompt comes up. The added time and disk activity
may allow the controller to flush its cache. If your caching
controller has a specific driver for SCO and you're using that
driver, then it can communicate with the operating system to ensure
that its buffers are all flushed, and this problem does not
Note that using a caching hard drive controller on a caching
operating system is generally of little or no use, though there are
certainly some cases in which it makes a significant performance
difference (but only by defeating the order in which write requests
were made by the kernel or the application, possibly decreasing
data integrity somewhat if the system crashes).
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