Hello,
Thank you for your really appreciated advice.
I confirm that I misunderstood what "applies to all instances" means.So now
seems clear. Thanks
But there is something I don't understand.
I have two templates.The second one which is a simple instance of a tail >
/dev/ttyX under tail@.serviceI renamed it to foo@.service (I don't have
something which have foo* or bar* as name and previous tail@.service doesn't
not exist anymore)
I have this [Install]
Section:WantedBy=getty.targetDefaultInstance=tty12Alias=bar@.service
systemctl enable foo@tty12.service> Created symlink
/etc/systemd/system/bar@tty12.service => /etc/systemd/system/foo@.service>
Created symlink /etc/systemd/system/getty.target.wants/foo@tty12.service =>
/etc/systemd/system/foo@service
Systemctl status bar@tty12.service> Loaded: error (Reason: Unit
bar@tty12.service to load properly: File Exists)
Systemctl start bar@tty12.service = KO> Failed to start bar@tty12.service: Unit
bar@tty12.service failed to load properly: File Exists.> See system logs and
systemctl status bar@tty12.service for details
Systemctl start foo@tty12.service = OK
RegardsHans
Le jeudi 22 avril 2021 à 20:49:52 UTC+2, Mantas Mikulėnas
a écrit :
On Thu, Apr 22, 2021 at 9:18 PM Hans Gruber wrote:
Hello,
I am having problems with the aliases and "Alias=' directive related to the
template service unit.
According to https://www.freedesktop.org/software/systemd/man/systemd.unit.html
> "A template instance may only be aliased by another template instance, and
> the instance part must be identical. A template may be aliased by another
> template (in which case the alias applies to all instances of the template).
> As a special case, a template instance (e.g. "alias@inst.service") may be a
> symlink to different template (e.g. "template@inst.service"). In that case,
> just this specific instance is aliased, while other instances of the template
> (e.g. "alias@foo.service", "alias@bar.service") are not aliased. Those rule
> preserve the requirement that the instance (if any) is always uniquely
> defined for a given unit and all its aliases."
I have exactly these two cases and requirements and cannot find example.
> "A template may be aliased by another template (in which case the alias
>applies to all instances of the template)"
eg: How to create an alias using `Alias=` for a service template core@.service
which will have maybe 8 or 16 instances (eg: core@cpu01.service
core@cpu02.service ..) which will apply to all instances when enabled using eg
allcores@.service.
I think you're misunderstanding what "applies to all instances" means. It does
not give you a super-unit that controls all instances in unison -- rather, it
gives you a template alias that will provide an alias for *each instance
individually*.
But one instance is still aliased to one instance. For example, if you alias
foo@.service => bar@.service, then you automatically get foo@cpu1.service =>
bar@cpu1.service, and so on. That's what template aliases do.
If you want to control multiple instances at once, you might be looking for two
other features:1. Custom target units, which allow you to *start* all instances
at once;
2. Wildcard support in `systemctl` commands, which allows you to see the status
of all loaded instances at once (systemctl status "foo@*.service").
--
Mantas Mikulėnas ___
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