[systemd-devel] List all available units

[Václav Pavlín]

Lennart Poettering píše v St 08. 08. 2012 v 18:31 +0200:
> On Tue, 07.08.12 16:35, Václav Pavlín (vpavlin at redhat.com) wrote:
> 
> I am not sure we should include the units from "list-unit-files" in the
> output of "list-units", as this would increase the output quite a bit,
> and would be hardly helpful in many cases, and slow.

I didn't really meant to include output of one "list-uni*" parameter to
another. Those lists does not have much in common and, as You point out,
merged output could be slow.

> So, dunno, I am not entirely sure how to expose this best. We probably
> should get the interface right, and agree how this would be exposed to
> the user, before we actually think about implementing it. Neither of the
> three options I currently see (extend "systemctl list-units", extend
> "systemctl list-unit-files", add a new systemctl verb) are that
> pretty in my eyes.

I would vote for the "new systemctl verb" option.

> If we present the user with a list like this we probably should show a
> tree view of some kind since the unit file getty at .service might get
> instantiated a couple of times as "getty at tty1.service" and so on, and
> hence is in a tree-like relationship. 

I like the idea of the tree view, but I cannot imagine how it can help
to solve autocompletion problem. If I get it right, getty at .service is
template file, which cannot be manually instantiated, so it can be
omitted from the output (User cannot do anything with it, right?). On
the other hand, getty at tty1.service is an instance, which can be stopped,
restarted etc., and it will be listed in list-units output (and then in
merged output of new systemctl verb as well).

> Another option would be to add a notice about "systemctl
> list-unit-files" in the footer of "systemctl list-units". That should
> already be a big imprvoement, since most people probably interrpet the
> current advice of using "--all" like this.

It would be helpful, but, again, does not solve the autocompletion
problem.

> Another option would be to add "systemctl complete" as hidden option for
> usage only by bash completion, that does the merging.

This makes sense to me. It could be even something like "systemctl
list-autocomplete-units".

> Yes, storing this in a hashmap does make sense. But really, before we
> get hacking we should think about the UI of this.

Ok, I will wait for your agreement.

Václav