[systemd-devel] /usr vs /etc for default distro units enablement

Lennart Poettering lennart at poettering.net
Mon Dec 1 16:59:14 PST 2014

On Fri, 28.11.14 11:15, Didier Roche (didrocks at ubuntu.com) wrote:

> The distribution comes preinstalled with one dm, enable * -> enable it, have
> the Alias=display-manager.service picking the right one.
> However, let's say the user installed then another dm, what happens? Both
> will be enabled if we systemctl preset <new_service> (as the discussion was
> to remove our debian enable <service> that was conditioned on the
> postinst).

"systemctl preset" will fail if there are already conflicting
symlinks. Hence the first installed DM wins, the second loses.

> I don't think we should have systemctl preset <new_service> running under
> any condition as a wipe of /etc and then "systemctl preset-all" would give a
> potential different result (I'm not even sure how this will work with those
> alias, the first matching the alias wins and get the symlinks?)

Dont follow? "wipe"?

> We can of course have an ubuntu-desktop.preset which disables all dms by
> lightdm, and an ubuntu-gnome.preset which disables all dms but gdm (and
> having those settings conflicting with each other), but it's seems that for
> every aliases, we need to maintain such a list (as we enable * by
> default)?

Not following here. Different flavours of Ubuntu should probably just
ship different preset files. (Or well, the main ubuntu should ship one
that enables lightdm, and then the gnome flavour ship another preset
file, with a lower name, tht overries the lightdm line, and enables
gdm instead).


Lennart Poettering, Red Hat

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