[systemd-devel] journal entries for most recent pid?

[Zbigniew Jędrzejewski-Szmek]

On Thu, Apr 24, 2014 at 08:59:46AM +0200, Lennart Poettering wrote:
> On Tue, 25.03.14 15:59, Peter Hutterer (peter.hutterer at who-t.net) wrote:
> 
> > I can't seem to find this in the documentation, so I do wonder if it exists:
> > is there an equivalent to journalctl -b -1 that lists the log of the most
> > recent pid?
> > 
> > Specifically I'd like to run journalctl /usr/bin/Xorg --pid -1 or similar to
> > get users to attach the most recent log file instead of having to provide
> > _PID manually.
> 
> Hmm, I can see the usecase for that, but I am not sure how we could
> implement this nicely...
> 
> To implement this we'd have to store the starttime of each PID in the
> database, and then order by that. And then we'd have to figure out the
> most recent one, probably in a similar fashion as we already allow this
> boot ids...
> 
> I have added this now to the TODO list, but don't hold your breath...
I've been thinking about this too, and actually for the same usecase (i.e.
logs from X). I think we should teach various programs like X to logs an
equivalent of _BOOT_ID (e.g. "XORG_RUN_ID"), and then systemctl could be
extended to support it the same -b / --list-boots, except that the
user would specify the tag (e.g. XORG_RUN_ID) to sort on. The
advantage would be that e.g. Xorg and gdm could agree to use the same
tag for the same session, thus making is easy to correlate log
messages.

Zbyszek