Bug#746577: closed by Michael Biebl <biebl at debian.org> (Re: Bug#746577: systemd-sysv: for upgrade safety, systemd-sysv and sysvinit-core must be coinstallable)

[Zack Weinberg]

On 05/06/2014 08:08 AM, Tollef Fog Heen wrote:
> ]] Zack Weinberg 
> 
>> On Mon, May 5, 2014 at 5:40 PM, Tollef Fog Heen <tfheen at err.no> wrote:
>>> ]] Zack Weinberg
>>>> Fundamentally what I want is a bulletproof procedure for reverting to
>>>> sysvinit in case something goes wrong.
>>>
>>> Sounds like you're arguing that sysvinit-core should no longer ship
>>> /sbin/init, then, so systemd-sysv doesn't have to conflict with it.
>>
>> Wouldn't that make the sysvinit implementation of /sbin/init
>> completely unavailable?  This is an earnest question.  I do not have
>> access to package contents right now.
> 
> No, to revert you'd boot with init=/sbin/sysvinit.

Ah, I understand now.  Yes, this + systemd-sysv and upstart *also* stop
shipping /sbin/init (it becomes a symlink under control of the
administrator) + documentation would be a satisfactory conclusion as far
as I'm concerned.  If we were to also move 'reboot' and friends to a
shared utilities package, that might make the systemd-sysv package
unnecessary.

Ideally, also, if systemd is installed on a system that is currently
running sysvinit, that doesn't change what /sbin/init points to; the
administrator has to do that as a separate operation.  This provides an
additional bit of defense against unforeseen problems with local
customizations -- the admin can look into them in their own time rather
than immediately.

>> Note that coinstallability is not enough -- the bulletproof procedure
>> (e.g. "update-init-system") must also be implemented, shipped, and
>> documented.
> 
> I have still not seen any reason whatsoever for this to be a command
> rather than just changing a configuration file.

I have no problem with that.  I suggested a command because I thought
the switch might be more complicated than just changing what /sbin/init
is symlinked to, but right now it looks to me like that should be enough.

zw


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