In message <Pine.NEB.4.33.0106262017350.16838-100000@tautology.immanent.net>, F
rederick Bruckman writes:
>On Tue, 26 Jun 2001, maximum entropy wrote:
>
>> >		tar -xvzpf $i -C /
>[...]
>> And you really don't need to say "--unlink", since that has been the
>> default for several years.
>
>Speaking of "defaults for years", sysinstall supports upgrades now. In
>addition to all of the above, it will move your old "/etc" to
>"/etc.old", install the new "/etc", and delete any obsolete files
>(binaries that have changed location &c). It's fairly painless if you
>can get the sets over ftp, or nfs, or if you can put them on a
>seperate partition.

Yes, but there's a bad failure mode...  If it can't find the upgrade 
tarballs -- say, because the network is down, or because you don't know 
the magic name of /usr during an upgrade (I think it's /mnt2), and you 
have to abort, you're left with a nearly empty /etc and a populated
/etc.old -- it doesn't restore things to where they were before.  Then, 
if you are bit hasty and remove the wrong one -- ask me how I know what 
happens next....  Better yet, don't ask.

		--Steve Bellovin, http://www.research.att.com/~smb