[ On Friday, June 20, 2003 at 08:50:32 (-0500), Frederick Bruckman wrote: ]
> Subject: Re: updating, build and install order
>
> On Fri, 20 Jun 2003, William Allen Simpson wrote:
> 
> >   mv /netbsd /netbsd.old
> >   mv ../obj/sys/arch/i386/compile/GENERIC/netbsd /
> 
> With that, there's a chance that an inopportune power failure could
> render the system unbootable. Better (IMO):
> 
>     rm /netbsd.old
>     ln /netbsd /netbsd.old
>     sync; sync
>     install -cpr ../obj/sys/arch/i386/compile/GENERIC/netbsd /
>     sync; sync

"sync; sleep 5"  would be far better -- "sync; sync" is effectively the
very same as just one "sync".

Better yet:  just get a UPS!  :-)

Remember that the original reason UNIX System admins were instructed to
type:

	sync
	sync
	sync

(i.e. type three separate "sync" commands, NOT "sync;sync;sync")

before halting the CPU was that it took long enough to type the second
two commands, and to get the prompt back each time, on a real Teletype
ASR33, or similar clunker of a console, that the first command would
have actually finished working in the background by the time you got
around to halting the CPU.  (the time it took to get from the console to
the CPU front panel probably also helped....  :-)

Then again for modern computers there's the reason given here:

	<URL:http://www.schedler.org/cookie/why-sync-3-times.html>

:-)

-- 
								Greg A. Woods

+1 416 218-0098;            <g.a.woods@ieee.org>;           <woods@robohack.ca>
Planix, Inc. <woods@planix.com>; VE3TCP; Secrets of the Weird <woods@weird.com>