[systemd-devel] Documentation question

Lennart Poettering lennart at poettering.net
Wed Feb 29 05:26:07 PST 2012

On Wed, 29.02.12 06:00, David Lambert (dave at lambsys.com) wrote:

> On 02/28/2012 10:09 PM, Mathieu Bridon wrote:
> >Do you have the folder /var/log/journal on your system?
> >
> >If it exists, systemd-journald will write logs there, otherwise it will
> >write them to /run/journal
> >
> >And since /run is mounted as tmpfs, that could explain the memory usage
> >you are seeing?
> >
> Thanks Mathieu - that was the issue! Two more questions, however:
> 1) What is the preferred method for turning off logging, or at least
> redirecting it to /dev/null? I have an embedded system with very
> limited resources.

Turning logging off entirely is currently not supported, but it probably
makes sense to make this possible. I have now added this to the TODO

You can put limits on the log size however, for example via
SystemMaxUse=64M or SystemKeepFree=500M or suchlike.

Note that there is currently a minimum file size of 64K enforced. (And
if something stores an entry larger than this the disk space consumption
might be beyond 64K temporarily)

> 2) What is the best resource for systemd documentation? For example,
> I still have not found a man page for systemd-journald.conf

Well, there's a huge body of documentation, for example, all the man
pages here:


Or the blog stories which are linked from the systemd home page (look
for systemd for Administrators):


However, I haven't found time to document the journal yet. Will do
before F17 is released.


Lennart Poettering - Red Hat, Inc.

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