<?xml version='1.0'?> <!--*-nxml-*-->
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
-
-<!--
- This file is part of systemd.
-
- Copyright 2010 Lennart Poettering
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
-
- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
--->
+<!-- SPDX-License-Identifier: LGPL-2.1+ -->
<refentry id="systemd-journald.service">
<refentryinfo>
<title>systemd-journald.service</title>
<productname>systemd</productname>
-
- <authorgroup>
- <author>
- <contrib>Developer</contrib>
- <firstname>Lennart</firstname>
- <surname>Poettering</surname>
- <email>lennart@poettering.net</email>
- </author>
- </authorgroup>
</refentryinfo>
<refmeta>
<listitem><para>Structured system log messages via the native
Journal API, see
- <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>4</manvolnum></citerefentry></para></listitem>
+ <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry></para></listitem>
<listitem><para>Standard output and standard error of service units. For further details see
below.</para></listitem>
for more information about the collected metadata.
</para>
- <para>Log data collected by the journal is primarily text-based
- but can also include binary data where necessary. All objects
- stored in the journal can be up to 2^64-1 bytes in size.</para>
+ <para>Log data collected by the journal is primarily text-based but can also include binary data where
+ necessary. Individual fields making up a log record stored in the journal may be up to 2^64-1 bytes in size.</para>
+
+ <para>The journal service stores log data either persistently below <filename>/var/log/journal</filename> or in a
+ volatile way below <filename>/run/log/journal/</filename> (in the latter case it is lost at reboot). By default, log
+ data is stored persistently if <filename>/var/log/journal/</filename> exists during boot, with an implicit fallback
+ to volatile storage otherwise. Use <varname>Storage=</varname> in
+ <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> to configure
+ where log data is placed, independently of the existence of <filename>/var/log/journal/</filename>.</para>
- <para>By default, the journal stores log data in
- <filename>/run/log/journal/</filename>. Since
- <filename>/run/</filename> is volatile, log data is lost at
- reboot. To make the data persistent, it is sufficient to create
- <filename>/var/log/journal/</filename> where
- <filename>systemd-journald</filename> will then store the
- data:</para>
+ <para>On systems where <filename>/var/log/journal/</filename> does not exist yet but where persistent logging is
+ desired (and the default <filename>journald.conf</filename> is used), it is sufficient to create the directory, and
+ ensure it has the correct access modes and ownership:</para>
<programlisting>mkdir -p /var/log/journal
systemd-tmpfiles --create --prefix /var/log/journal</programlisting>
<para>If <filename>systemd-journald.service</filename> is stopped, the stream connections associated with all
services are terminated. Further writes to those streams by the service will result in <constant>EPIPE</constant>
errors. In order to react gracefully in this case it is recommended that programs logging to standard output/error
- ignore such errors. If the the <constant>SIGPIPE</constant> UNIX signal handler is not blocked or turned off, such
+ ignore such errors. If the <constant>SIGPIPE</constant> UNIX signal handler is not blocked or turned off, such
write attempts will also result in such process signals being generated, see
<citerefentry><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>. To mitigate this issue,
systemd service manager explicitly turns off the <constant>SIGPIPE</constant> signal for all invoked processes by
transports listed above, which are inherently record based and where the metadata is always associated with the
individual record.</para>
- <para>In addition to the the implicit standard output/error logging of services, stream logging is also available
+ <para>In addition to the implicit standard output/error logging of services, stream logging is also available
via the <citerefentry><refentrytitle>systemd-cat</refentrytitle><manvolnum>1</manvolnum></citerefentry> command
line tool.</para>
<para>Currently, the number of parallel log streams <filename>systemd-journald</filename> will accept is limited to
- 4096. When this limit is reached further log streams may be established but will receieve
+ 4096. When this limit is reached further log streams may be established but will receive
<constant>EPIPE</constant> right from the beginning.</para>
</refsect1>
<para>Journal files are, by default, owned and readable by the
<literal>systemd-journal</literal> system group but are not
- writable. Adding a user to this group thus enables her/him to read
+ writable. Adding a user to this group thus enables them to read
the journal files.</para>
- <para>By default, each logged in user will get her/his own set of
+ <para>By default, each logged in user will get their own set of
journal files in <filename>/var/log/journal/</filename>. These
files will not be owned by the user, however, in order to avoid
that the user can write to them directly. Instead, file system
<varlistentry>
<term><filename>/etc/systemd/journald.conf</filename></term>
- <listitem><para>Configure
- <command>systemd-journald</command>
- behavior. See
+ <listitem><para>Configure <command>systemd-journald</command> behavior. See
<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para></listitem>
</varlistentry>
<term><filename>/var/log/journal/<replaceable>machine-id</replaceable>/*.journal</filename></term>
<term><filename>/var/log/journal/<replaceable>machine-id</replaceable>/*.journal~</filename></term>
- <listitem><para><command>systemd-journald</command> writes
- entries to files in
+ <listitem><para><command>systemd-journald</command> writes entries to files in
<filename>/run/log/journal/<replaceable>machine-id</replaceable>/</filename>
or
<filename>/var/log/journal/<replaceable>machine-id</replaceable>/</filename>
<filename>/var/log/journal</filename> is not available, or
when <option>Storage=volatile</option> is set in the
<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- configuration file.</para></listitem>
+ configuration file.</para>
+
+ <para>When <filename>systemd-journald</filename> ceases writing to a journal file,
+ it will be renamed to <literal><replaceable>original-name</replaceable>@<replaceable>suffix.journal</replaceable></literal>
+ (or <literal><replaceable>original-name</replaceable>@<replaceable>suffix.journal~</replaceable></literal>).
+ Such files are "archived" and will not be written to any more.</para>
+
+ <para>In general, it is safe to read or copy any journal file (active or archived).
+ <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ and the functions in the
+ <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ library should be able to read all entries that have been fully written.</para>
+
+ <para><filename>systemd-journald</filename> will automatically remove the oldest
+ archived journal files to limit disk use. See <varname>SystemMaxUse=</varname>
+ and related settings in
+ <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+ </para></listitem>
</varlistentry>
<varlistentry>
<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-coredump</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry project='die-net'><refentrytitle>setfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>4</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<command>pydoc systemd.journal</command>
</para>
</refsect1>
projects / thirdparty / systemd.git / blobdiff