[systemd-devel] custom var in sd_notify

[Lennart Poettering]

On Mo, 26.02.18 08:09, Mantas Mikulėnas (grawity at gmail.com) wrote:

> > Daemons can choose to send additional variables. However, it is recommended
> > to prefix variable names not listed above with X_.
> > So naturally i tried
> >
> > sd_notify(0, "X_ANSWER=42")
> >
> > and apparently systemd has no problem with that, but my questions are 2
> > now:
> >
> > 1) What does systemd do with this information?
> >
> 
> Nothing. The documentation just says in other words that "the init system
> must not reject packets with unknown variables", but doesn't say that
> systemd or any other init will store all of them anywhere.

Currently we indeed ignore those unknown variables entirely. It has
been requested that we expose these variables on the bus somehow. I
think that would be an OK addition, but we need to think about the
lifecycle of those vars then so that the vars we collect don't grow
without bounds.

Lennart

-- 
Lennart Poettering, Red Hat