<?xml version='1.0'?> <!--*-nxml-*--> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//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/>. --> <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> <refentrytitle>systemd-journald.service</refentrytitle> <manvolnum>8</manvolnum> </refmeta> <refnamediv> <refname>systemd-journald.service</refname> <refname>systemd-journald.socket</refname> <refname>systemd-journald</refname> <refpurpose>Journal service</refpurpose> </refnamediv> <refsynopsisdiv> <para><filename>systemd-journald.service</filename></para> <para><filename>systemd-journald.socket</filename></para> <para><filename>/usr/lib/systemd/systemd-journald</filename></para> </refsynopsisdiv> <refsect1> <title>Description</title> <para><filename>systemd-journald</filename> is a system service that collects and stores logging data. It creates and maintains structured, indexed journals based on logging information that is received from the kernel, from user processes via the libc <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> call, from STDOUT/STDERR of system services or via its native API. It will implicitly collect numerous meta data fields for each log messages in a secure and unfakeable way. See <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> for more information about the collected meta data. </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>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><filename>systemd-journald</filename> will forward all received log messages to the AF_UNIX SOCK_DGRAM socket <filename>/run/systemd/journal/syslog</filename> (if it exists) which may be used by UNIX syslog daemons to process the data further.</para> <para>See <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> for information about the configuration of this service.</para> </refsect1> <refsect1> <title>Signals</title> <variablelist> <varlistentry> <term>SIGUSR1</term> <listitem><para>Request that journal data from <filename>/run/</filename> is flushed to <filename>/var/</filename> in order to make it persistent (if this is enabled). This may be used after <filename>/var/</filename> is mounted, but is generally not required since the first journal write when <filename>/var/</filename> becomes writable triggers the flushing anyway.</para></listitem> </varlistentry> <varlistentry> <term>SIGUSR2</term> <listitem><para>Request immediate rotation of the journal files.</para></listitem> </varlistentry> </variablelist> </refsect1> <refsect1> <title>Kernel Command Line</title> <para>A few configuration parameters from <filename>journald.conf</filename> may be overriden on the kernel command line:</para> <variablelist> <varlistentry> <term><varname>systemd.journald.forward_to_syslog=</varname></term> <term><varname>systemd.journald.forward_to_kmsg=</varname></term> <term><varname>systemd.journald.forward_to_console=</varname></term> <listitem><para>Enables/disables forwarding of collected log messages to syslog, the kernel log buffer or the system console. </para> <para>See <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> for information about these settings.</para> </listitem> </varlistentry> </variablelist> </refsect1> <refsect1> <title>See Also</title> <para> <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry> </para> </refsect1> </refentry>