[systemd-devel] journalctl --since today --follow weirdness

[Lennart Poettering]

On Wed, 23.04.14 16:12, Colin Guthrie (gmane at colin.guthr.ie) wrote:

> Hiya,
> 
> A colleague pointed out an oddity in journalctl --since today --follow
> output.
> 
> It seems the two arguments somewhat contradict each other: one asks for
> all the output for today and the other asks for all future messages, but
> using them together should obviously behave in a somewhat sensible way!
> 
> What I was expecting was basically the same as what journalctl --follow
> would produce, but excluding any output not from today. e.g. if the
> first 5 lines of a standard journalctl -f happened to be from yesterday,
> then I'd expect only the 5 lines from today to be printed and then any
> further output as it happens.

What actually happens is that the output will show you everything from
today, and when it is done with that continue with a live output. To me
this appears as the right thing to do, no? To me --follow is kinda the
little add-on just says "and then continue live"...

Of course, this definition means that --until and --follow are
contradictory when combined, so we should probably just check for that
and exit with an error....

> What appears to happen instead is that you get the first 10 lines from
> the day (i.e. after midnight) and then *all* lines from today following
> that after a small delay (likely not a deliberate delay - just whatever
> overhead it takes to lookup and output the data), thus taking quite some
> time to page through which is definitely not what you expect from
> --follow, but arguably what you would expect from --since today. It's
> only the delay before full output that makes this very much feel like a
> bug rather than intentional (i.e. --since having a higher precedence
> than --follow's 10 line limit!)

Hmm, I am actually seeing that I get the full output of today, plus
anything that happens afterwards, this looks quite ok to me... 

> This is with a recent version of the 208-stable branch.

can you check with git?

Lennart

-- 
Lennart Poettering, Red Hat