[systemd-devel] How to suppress "A start job is running for offline-updates" knight-rider status output?

[Mantas Mikulėnas]

On Tue, Feb 26, 2019 at 7:29 PM Hans de Goede <hdegoede at redhat.com> wrote:

> Hi All,
>
> As part of improving the boot experience:
> https://fedoraproject.org/wiki/Changes/FlickerFreeBoot
> https://hansdegoede.livejournal.com/20119.html
>
> I took a look at how applying offline updates looks
> when pressing ESC to get the detailed view, pk-offline-update
> then prints "dnf update" like output, but at the same time
> systemd is printing:
>
> [   ***] A start job is running for offline-updates
>
> Messages to the console, the 2 get intermixed and this looks
> quite bad and makes the status update of the actual
> update process almost impossible to follow.
>
> Is there something which I can put in the
>
> /lib/systemd/system/system-update.target.wants/packagekit-offline-update.service
> service file to suppress the knightrider status updates ?
>
>
I think the official name is "cylon eye status updates".

Hmm, I *thought* it was possible to disable this by something like
flock()'ing the console device, and systemd-fsck was supposed to do that in
order to avoid the job status from mixing with the "fsck: x% complete"
output. But it looks like that functionality was lost, or never present,
and indeed even systemd-fsck's output is trashed by the "job is running"
messages, from what I remember.

Looking at source code (manager_get_show_status, unit_needs_console,
exec_context_may_touch_console), the output should be disabled if at least
one currently active unit has a tty as its stdin/stdout, and/or any of the
tty_reset/tty_vhangup options enabled. So maybe StandardOutput=tty,
TTYPath=/dev/console would achieve this?

-- 
Mantas Mikulėnas
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