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Re: anticipating the upstart migration

* Gabor Gombas (gombasg@sztaki.hu) wrote:
> On Tue, Oct 10, 2006 at 05:25:57PM -0400, Eric Dorland wrote:
> > Shouldn't it be possible to move the alternatives around in an atomic
> > fashion? ln -sf bar foo.tmp ; mv foo.tmp foo . Or am I missing
> > something? 
> - If you set up the alternatives in preinst, then there is a time when
>   the symlink exists but the pointed binary hasn't been unpacked yet ->
>   unbootable system.
> - If you set up the alternatives in postinst, there is a time when there
>   is no /sbin/init at all -> unbootable system.

The second case is only true if the init providing packages conflict
with each other, which I don't think would necessarily be the case. 
> It's not enough to install a single link atomically. Unpacking
> /sbin/init.upstart AND setting the /sbin/init symlink AND setting the
> /etc/alternatives/init symlink _together_ would have to be atomic.

Eric Dorland <eric@kuroneko.ca>
ICQ: #61138586, Jabber: hooty@jabber.com
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