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7e07f37585
journald: turn ForwardToSyslog= off by default
After all, rsyslog and friends nowadays read their data directly from
the journal, hence the forwarding is unnecessary in most cases.
see 46b131574f
277 lines
11 KiB
XML
277 lines
11 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd-journald.service">
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<refentryinfo>
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<title>systemd-journald.service</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-journald.service</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-journald.service</refname>
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<refname>systemd-journald.socket</refname>
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<refname>systemd-journald-dev-log.socket</refname>
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<refname>systemd-journald-audit.socket</refname>
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<refname>systemd-journald</refname>
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<refpurpose>Journal service</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>systemd-journald.service</filename></para>
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<para><filename>systemd-journald.socket</filename></para>
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<para><filename>systemd-journald-dev-log.socket</filename></para>
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<para><filename>systemd-journald-audit.socket</filename></para>
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<para><filename>/usr/lib/systemd/systemd-journald</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><filename>systemd-journald</filename> is a system service
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that collects and stores logging data. It creates and maintains
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structured, indexed journals based on logging information that is
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received from a variety of sources:</para>
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<itemizedlist>
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<listitem><para>Kernel log messages, via kmsg</para></listitem>
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<listitem><para>Simple system log messages, via the libc
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<citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call</para></listitem>
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<listitem><para>Structured system log messages via the native
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Journal API, see
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<citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>4</manvolnum></citerefentry></para></listitem>
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<listitem><para>Standard output and standard error of system
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services</para></listitem>
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<listitem><para>Audit records, via the audit
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subsystem</para></listitem>
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</itemizedlist>
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<para>The daemon will implicitly collect numerous metadata fields
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for each log messages in a secure and unfakeable way. See
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<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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for more information about the collected metadata.
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</para>
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<para>Log data collected by the journal is primarily text-based
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but can also include binary data where necessary. All objects
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stored in the journal can be up to 2^64-1 bytes in size.</para>
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<para>By default, the journal stores log data in
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<filename>/run/log/journal/</filename>. Since
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<filename>/run/</filename> is volatile, log data is lost at
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reboot. To make the data persistent, it is sufficient to create
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<filename>/var/log/journal/</filename> where
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<filename>systemd-journald</filename> will then store the
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data:</para>
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<programlisting>mkdir -p /var/log/journal
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systemd-tmpfiles --create --prefix /var/log/journal</programlisting>
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<para>See
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<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for information about the configuration of this service.</para>
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</refsect1>
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<refsect1>
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<title>Signals</title>
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<variablelist>
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<varlistentry>
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<term>SIGUSR1</term>
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<listitem><para>Request that journal data from
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<filename>/run/</filename> is flushed to
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<filename>/var/</filename> in order to make it persistent (if
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this is enabled). This must be used after
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<filename>/var/</filename> is mounted, as otherwise log data
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from <filename>/run</filename> is never flushed to
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<filename>/var</filename> regardless of the configuration. The
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<command>journalctl --flush</command> command uses this signal
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to request flushing of the journal files, and then waits for
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the operation to complete. See
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<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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for details.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>SIGUSR2</term>
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<listitem><para>Request immediate rotation of the journal
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files. The <command>journalctl --rotate</command> command uses
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this signal to request journal file
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rotation.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>SIGRTMIN+1</term>
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<listitem><para>Request that all unwritten log data is written
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to disk. The <command>journalctl --sync</command> command uses
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this signal to trigger journal synchronization, and then waits
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for the operation to complete.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Kernel Command Line</title>
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<para>A few configuration parameters from
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<filename>journald.conf</filename> may be overridden on the kernel
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command line:</para>
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<variablelist class='kernel-commandline-options'>
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<varlistentry>
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<term><varname>systemd.journald.forward_to_syslog=</varname></term>
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<term><varname>systemd.journald.forward_to_kmsg=</varname></term>
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<term><varname>systemd.journald.forward_to_console=</varname></term>
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<term><varname>systemd.journald.forward_to_wall=</varname></term>
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<listitem><para>Enables/disables forwarding of collected log
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messages to syslog, the kernel log buffer, the system console
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or wall.
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</para>
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<para>See
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<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for information about these settings.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Access Control</title>
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<para>Journal files are, by default, owned and readable by the
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<literal>systemd-journal</literal> system group but are not
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writable. Adding a user to this group thus enables her/him to read
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the journal files.</para>
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<para>By default, each logged in user will get her/his own set of
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journal files in <filename>/var/log/journal/</filename>. These
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files will not be owned by the user, however, in order to avoid
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that the user can write to them directly. Instead, file system
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ACLs are used to ensure the user gets read access only.</para>
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<para>Additional users and groups may be granted access to journal
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files via file system access control lists (ACL). Distributions
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and administrators may choose to grant read access to all members
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of the <literal>wheel</literal> and <literal>adm</literal> system
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groups with a command such as the following:</para>
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<programlisting># setfacl -Rnm g:wheel:rx,d:g:wheel:rx,g:adm:rx,d:g:adm:rx /var/log/journal/</programlisting>
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<para>Note that this command will update the ACLs both for
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existing journal files and for future journal files created in the
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<filename>/var/log/journal/</filename> directory.</para>
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</refsect1>
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<refsect1>
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<title>Files</title>
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<variablelist>
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<varlistentry>
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<term><filename>/etc/systemd/journald.conf</filename></term>
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<listitem><para>Configure
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<command>systemd-journald</command>
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behavior. See
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<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>/run/log/journal/<replaceable>machine-id</replaceable>/*.journal</filename></term>
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<term><filename>/run/log/journal/<replaceable>machine-id</replaceable>/*.journal~</filename></term>
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<term><filename>/var/log/journal/<replaceable>machine-id</replaceable>/*.journal</filename></term>
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<term><filename>/var/log/journal/<replaceable>machine-id</replaceable>/*.journal~</filename></term>
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<listitem><para><command>systemd-journald</command> writes
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entries to files in
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<filename>/run/log/journal/<replaceable>machine-id</replaceable>/</filename>
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or
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<filename>/var/log/journal/<replaceable>machine-id</replaceable>/</filename>
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with the <literal>.journal</literal> suffix. If the daemon is
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stopped uncleanly, or if the files are found to be corrupted,
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they are renamed using the <literal>.journal~</literal>
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suffix, and <command>systemd-journald</command> starts writing
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to a new file. <filename>/run</filename> is used when
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<filename>/var/log/journal</filename> is not available, or
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when <option>Storage=volatile</option> is set in the
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<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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configuration file.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>/dev/kmsg</filename></term>
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<term><filename>/dev/log</filename></term>
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<term><filename>/run/systemd/journal/dev-log</filename></term>
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<term><filename>/run/systemd/journal/socket</filename></term>
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<term><filename>/run/systemd/journal/stdout</filename></term>
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<listitem><para>Sockets and other paths that
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<command>systemd-journald</command> will listen on that are
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visible in the file system. In addition to these, journald can
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listen for audit events using netlink.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-coredump</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry project='die-net'><refentrytitle>setfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>4</manvolnum></citerefentry>,
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<command>pydoc systemd.journal</command>
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</para>
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</refsect1>
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</refentry>
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