haltsys/reboot vrs. shutdown (was Re: init's untimely death.)

[Jonathan Bayer]

In article <2049 at egvideo.UUCP> edhew at egvideo.UUCP (Ed Hew) writes:
>In article <132 at tridom.uucp> you write:

>I'd greatly prefer to run shutdown.  It does all the above.  haltsys/reboot
>simply terminate the system.  It's the same effect as using the "big red
>switch", with the exception that the power is still on.  The one thing I
>don't really know is what it is exactly that haltsys does to terminate the
>system.  Anyone have any comments on how haltsys does it's job?


Haltsys _does_ do a clean shutdown of the system.  Shutdown does several
things.  It will wait a period of time, send messages to all the users,
send various kill commands to all the running processes to notify them
that the system is going down, do hard kills on the remaining processes,
and finally it executes haltsys.  

Quoting from the SCO Manual:

"The _haltyss_ utility performs a _uadmin()_ system call to flush out
pending disk I/O, mark the file systems clean, and halt the processor."


JB
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