systemd: targets which are runlevel-like
mattdm at mattdm.org
Tue Aug 24 22:07:35 UTC 2010
On Tue, Aug 24, 2010 at 11:49:56PM +0200, Lennart Poettering wrote:
> > Wait, so "--all" doesn't actually show me all targets, it shows me an
> > apparently-arbitrary list of some of the possible targets?
> It shows you all targets systemd knows about at that point in time.
> The list of thinkable targets you could activate is more ore less
> infinite, due to templating and stuff. I am pretty sure people would be
> pretty annoyed if we'd dump an infinite number of targets on your screen
> if you just type "systemctl".
Hmmm. I see what you are saying. And from a technical point of view, that
sounds reasonable. But here's what one part of me is hearing: wow, this new
systemd adds a whole bunch of complexity to running a machine.
That is a not a great selling point.
Is there a way to present _something_ more straightforward?
> > So, most targets are actually valid for 'isolate'? What if I go to
> > bluetooth.target?
> Hmm, we could add RefuseManualIsolate= to make uses like that
> impossible, while still allowing "start".
> /me adds this to his todo list.
Maybe the other way around -- postively list the targets which can be
manually "isolated"? (I still strongly suggest not using this term, by the
way.) Or did I take the FAQ's suggestion that this is what I want instead of
runlevels too far? My impression is that in the general state of things,
there's really only a small handful of *useful* targets for "isolate".
> Well, actually it's not really reliable. You don't see what is activated
> via udev (bluetoothd for example), or via dbus, or via cron or via
> anything else. It will strictly show you sysv services.
Okay, so, *THIS* is a big selling point for systemd. It knows about all that
stuff, so it can give me a nice simple list. Put things like that front and
center, and you'll have people lining up to switch.
(Minor detail that it doesn't, currently, give you that nice simple list.)
> If you are looking for something 1:1 eqivalent, then just use "systemadm"
> and click on "multi-user.target" and you can click through the services it
> will pull in.
That is something like a 1:500 equivalent.
> Or alternatively, use something like this:
> systemctl show -p "Wants" multi-user.target
Ok, cool, that's definitely a start. Can you put this in the FAQ?
Does it recurse? It'd be nice to have it in a nice list, too.
The other direction is useful as well. "When does gpm get started?" is
just "sbin/chkconfig --list gpm".
> > Can I get that with systemd?
> Well, we could add something that would allow you to calculate a
> transaction without actually executing this. This will give you a lot
> more than chkconfig ever did, as it would take into consideration what
> is already running, and more than just services that are started on
> boot-up, and the system state
> /me adds that to his todo list.
That would be awesome. Thanks. Again, this stuff should be front-and-center.
On the todo list: it should be able to show you the change from the current
state, and the change from nothing running at all.
> But don't expect this right-away, this is not completely trivial to
Trust me, thinking that any of this is trivial is not a problem I am having.
Matthew Miller <mattdm at mattdm.org>
Senior Systems Architect -- Instructional & Research Computing Services
Harvard School of Engineering & Applied Sciences
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