On Wed, 10.10.12 10:12, Richard W.M. Jones (rjones@xxxxxxxxxx) wrote: > On Wed, Oct 10, 2012 at 09:54:28AM +0100, Richard W.M. Jones wrote: > > On Wed, Oct 10, 2012 at 09:50:43AM +0200, Björn Persson wrote: > > > Lennart Poettering wrote: > > > > On Tue, 09.10.12 09:09, Chris Adams (cmadams@xxxxxxxxxx) wrote: > > > > > How do you read this log when the system is not running (e.g. > > > > > mounting filesystems of a drive on another system, running from a > > > > > rescue image, etc.)? > > > > > > > > journalctl -D <pathtothejournalfiles> > > > > > > So the rescue system (which might not always be Fedora) must have > > > journalctl installed. Is the file format stable, or can it break if the > > > rescue system has a different version of journalctl? Is the format > > > perchance even documented so that other tools for reading logs could be > > > written? > > > > This would be essential for libguestfs tools to parse logs out of > > guests (we do it now by reading /var/log/messages etc which has all of > > the properties you state). > > I checked out the code, and it does seem as if the format is intended > to be backwards compatible. It uses a set of filesystem-like > "compatible" and "incompatible" flags, so presumably a sufficiently > recent journalctl would be able to read any previous version of the > binary file format. > > It would be nice to have this confirmed, and indeed enshrined in the > policy of the journal, because it is IMHO essential that the binary > log files will always be readable. Yes, the compatible and incompatible flag bit fields are precisely to provide good compatibility as the format evolves. Lennart -- Lennart Poettering - Red Hat, Inc. -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
