man/systemd-journald.service.xml - systemd-stable - Rivoreo Source Code Repositories

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 <refentry id="systemd-journald.service">

   <refentryinfo>
     <title>systemd-journald.service</title>
     <productname>systemd</productname>
   </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-dev-log.socket</refname>
     <refname>systemd-journald-audit.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>systemd-journald-dev-log.socket</filename></para>
     <para><filename>systemd-journald-audit.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 a variety of sources:</para>

     <itemizedlist>
       <listitem><para>Kernel log messages, via kmsg</para></listitem>

       <listitem><para>Simple system log messages, via the <filename>libc</filename> <citerefentry
       project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
       call</para></listitem>

       <listitem><para>Structured system log messages via the native
       Journal API, see
       <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>

       <listitem><para>Audit records, originating from the kernel audit subsystem</para></listitem>
     </itemizedlist>

     <para>The daemon will implicitly collect numerous metadata 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 metadata.
     </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>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>See
     <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
     for information about the configuration of this service.</para>
   </refsect1>

   <refsect1>
     <title>Stream logging</title>

     <para>The systemd service manager invokes all service processes with standard output and standard error connected
     to the journal by default. This behaviour may be altered via the
     <varname>StandardOutput=</varname>/<varname>StandardError=</varname> unit file settings, see
     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details. The
     journal converts the log byte stream received this way into individual log records, splitting the stream at newline
     (<literal>\n</literal>, ASCII <constant>10</constant>) and <constant>NUL</constant> bytes.</para>

     <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 <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
     default (this may be changed for each unit individually via the <varname>IgnoreSIGPIPE=</varname> option, see
     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
     details). After the standard output/standard error streams have been terminated they may not be recovered until the
     services they are associated with are restarted. Note that during normal operation,
     <filename>systemd-journald.service</filename> stores copies of the file descriptors for those streams in the
     service manager. If <filename>systemd-journald.service</filename> is restarted using <command>systemctl
     restart</command> or equivalent operation instead of a pair of separate <command>systemctl stop</command> and
     <command>systemctl start</command> commands (or equivalent operations), these stream connections are not terminated
     and survive the restart. It is thus safe to restart <filename>systemd-journald.service</filename>, but stopping it
     is not recommended.</para>

     <para>Note that the log record metadata for records transferred via such standard output/error streams reflect the
     metadata of the peer the stream was originally created for. If the stream connection is passed on to other
     processes (such as further child processes forked off the main service process), the log records will not reflect
     their metadata, but will continue to describe the original process. This is different from the other logging
     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 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 receive
     <constant>EPIPE</constant> right from the beginning.</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 must be used after
         <filename>/var/</filename> is mounted, as otherwise log data
         from <filename>/run</filename> is never flushed to
         <filename>/var</filename> regardless of the configuration. The
         <command>journalctl --flush</command> command uses this signal
         to request flushing of the journal files, and then waits for
         the operation to complete. See
         <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
         for details.</para></listitem>
       </varlistentry>

       <varlistentry>
         <term>SIGUSR2</term>

         <listitem><para>Request immediate rotation of the journal
         files. The <command>journalctl --rotate</command> command uses
         this signal to request journal file
         rotation.</para></listitem>
       </varlistentry>

       <varlistentry>
         <term>SIGRTMIN+1</term>

         <listitem><para>Request that all unwritten log data is written
         to disk. The <command>journalctl --sync</command> command uses
         this signal to trigger journal synchronization, and then waits
         for the operation to complete.</para></listitem>
       </varlistentry>
     </variablelist>
   </refsect1>

   <refsect1>
     <title>Kernel Command Line</title>

     <para>A few configuration parameters from
     <filename>journald.conf</filename> may be overridden on the kernel
     command line:</para>

     <variablelist class='kernel-commandline-options'>
       <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>
         <term><varname>systemd.journald.forward_to_wall=</varname></term>

         <listitem><para>Enables/disables forwarding of collected log
         messages to syslog, the kernel log buffer, the system console
         or wall.
         </para>

         <para>See
         <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
         for information about these settings.</para>
         </listitem>

       </varlistentry>
     </variablelist>
   </refsect1>

   <refsect1>
     <title>Access Control</title>

     <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 them to read
     the journal files.</para>

     <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
     ACLs are used to ensure the user gets read access only.</para>

     <para>Additional users and groups may be granted access to journal
     files via file system access control lists (ACL). Distributions
     and administrators may choose to grant read access to all members
     of the <literal>wheel</literal> and <literal>adm</literal> system
     groups with a command such as the following:</para>

     <programlisting># setfacl -Rnm g:wheel:rx,d:g:wheel:rx,g:adm:rx,d:g:adm:rx /var/log/journal/</programlisting>

     <para>Note that this command will update the ACLs both for
     existing journal files and for future journal files created in the
     <filename>/var/log/journal/</filename> directory.</para>
   </refsect1>

   <refsect1>
     <title>Files</title>

     <variablelist>
       <varlistentry>
         <term><filename>/etc/systemd/journald.conf</filename></term>

         <listitem><para>Configure <command>systemd-journald</command> behavior. See
         <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
         </para></listitem>
       </varlistentry>

       <varlistentry>
         <term><filename>/run/log/journal/<replaceable>machine-id</replaceable>/*.journal</filename></term>
         <term><filename>/run/log/journal/<replaceable>machine-id</replaceable>/*.journal~</filename></term>
         <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
         <filename>/run/log/journal/<replaceable>machine-id</replaceable>/</filename>
         or
         <filename>/var/log/journal/<replaceable>machine-id</replaceable>/</filename>
         with the <literal>.journal</literal> suffix. If the daemon is
         stopped uncleanly, or if the files are found to be corrupted,
         they are renamed using the <literal>.journal~</literal>
         suffix, and <command>systemd-journald</command> starts writing
         to a new file. <filename>/run</filename> is used when
         <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>

         <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>
         <term><filename>/dev/kmsg</filename></term>
         <term><filename>/dev/log</filename></term>
         <term><filename>/run/systemd/journal/dev-log</filename></term>
         <term><filename>/run/systemd/journal/socket</filename></term>
         <term><filename>/run/systemd/journal/stdout</filename></term>

         <listitem><para>Sockets and other paths that
         <command>systemd-journald</command> will listen on that are
         visible in the file system. In addition to these, journald can
         listen for audit events using netlink.</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>,
       <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>3</manvolnum></citerefentry>,
       <command>pydoc systemd.journal</command>
     </para>
   </refsect1>

 </refentry>
	<?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">

	<!--
	SPDX-License-Identifier: LGPL-2.1+
	-->

	<refentry id="systemd-journald.service">

	<refentryinfo>
	<title>systemd-journald.service</title>
	<productname>systemd</productname>
	</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-dev-log.socket</refname>
	<refname>systemd-journald-audit.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>systemd-journald-dev-log.socket</filename></para>
	<para><filename>systemd-journald-audit.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 a variety of sources:</para>

	<itemizedlist>
	<listitem><para>Kernel log messages, via kmsg</para></listitem>

	<listitem><para>Simple system log messages, via the <filename>libc</filename> <citerefentry
	project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
	call</para></listitem>

	<listitem><para>Structured system log messages via the native
	Journal API, see
	<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>

	<listitem><para>Audit records, originating from the kernel audit subsystem</para></listitem>
	</itemizedlist>

	<para>The daemon will implicitly collect numerous metadata 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 metadata.
	</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>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>See
	<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
	for information about the configuration of this service.</para>
	</refsect1>

	<refsect1>
	<title>Stream logging</title>

	<para>The systemd service manager invokes all service processes with standard output and standard error connected
	to the journal by default. This behaviour may be altered via the
	<varname>StandardOutput=</varname>/<varname>StandardError=</varname> unit file settings, see
	<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details. The
	journal converts the log byte stream received this way into individual log records, splitting the stream at newline
	(<literal>\n</literal>, ASCII <constant>10</constant>) and <constant>NUL</constant> bytes.</para>

	<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 <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
	default (this may be changed for each unit individually via the <varname>IgnoreSIGPIPE=</varname> option, see
	<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
	details). After the standard output/standard error streams have been terminated they may not be recovered until the
	services they are associated with are restarted. Note that during normal operation,
	<filename>systemd-journald.service</filename> stores copies of the file descriptors for those streams in the
	service manager. If <filename>systemd-journald.service</filename> is restarted using <command>systemctl
	restart</command> or equivalent operation instead of a pair of separate <command>systemctl stop</command> and
	<command>systemctl start</command> commands (or equivalent operations), these stream connections are not terminated
	and survive the restart. It is thus safe to restart <filename>systemd-journald.service</filename>, but stopping it
	is not recommended.</para>

	<para>Note that the log record metadata for records transferred via such standard output/error streams reflect the
	metadata of the peer the stream was originally created for. If the stream connection is passed on to other
	processes (such as further child processes forked off the main service process), the log records will not reflect
	their metadata, but will continue to describe the original process. This is different from the other logging
	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 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 receive
	<constant>EPIPE</constant> right from the beginning.</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 must be used after
	<filename>/var/</filename> is mounted, as otherwise log data
	from <filename>/run</filename> is never flushed to
	<filename>/var</filename> regardless of the configuration. The
	<command>journalctl --flush</command> command uses this signal
	to request flushing of the journal files, and then waits for
	the operation to complete. See
	<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
	for details.</para></listitem>
	</varlistentry>

	<varlistentry>
	<term>SIGUSR2</term>

	<listitem><para>Request immediate rotation of the journal
	files. The <command>journalctl --rotate</command> command uses
	this signal to request journal file
	rotation.</para></listitem>
	</varlistentry>

	<varlistentry>
	<term>SIGRTMIN+1</term>

	<listitem><para>Request that all unwritten log data is written
	to disk. The <command>journalctl --sync</command> command uses
	this signal to trigger journal synchronization, and then waits
	for the operation to complete.</para></listitem>
	</varlistentry>
	</variablelist>
	</refsect1>

	<refsect1>
	<title>Kernel Command Line</title>

	<para>A few configuration parameters from
	<filename>journald.conf</filename> may be overridden on the kernel
	command line:</para>

	<variablelist class='kernel-commandline-options'>
	<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>
	<term><varname>systemd.journald.forward_to_wall=</varname></term>

	<listitem><para>Enables/disables forwarding of collected log
	messages to syslog, the kernel log buffer, the system console
	or wall.
	</para>

	<para>See
	<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
	for information about these settings.</para>
	</listitem>

	</varlistentry>
	</variablelist>
	</refsect1>

	<refsect1>
	<title>Access Control</title>

	<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 them to read
	the journal files.</para>

	<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
	ACLs are used to ensure the user gets read access only.</para>

	<para>Additional users and groups may be granted access to journal
	files via file system access control lists (ACL). Distributions
	and administrators may choose to grant read access to all members
	of the <literal>wheel</literal> and <literal>adm</literal> system
	groups with a command such as the following:</para>

	<programlisting># setfacl -Rnm g:wheel:rx,d:g:wheel:rx,g:adm:rx,d:g:adm:rx /var/log/journal/</programlisting>

	<para>Note that this command will update the ACLs both for
	existing journal files and for future journal files created in the
	<filename>/var/log/journal/</filename> directory.</para>
	</refsect1>

	<refsect1>
	<title>Files</title>

	<variablelist>
	<varlistentry>
	<term><filename>/etc/systemd/journald.conf</filename></term>

	<listitem><para>Configure <command>systemd-journald</command> behavior. See
	<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
	</para></listitem>
	</varlistentry>

	<varlistentry>
	<term><filename>/run/log/journal/<replaceable>machine-id</replaceable>/*.journal</filename></term>
	<term><filename>/run/log/journal/<replaceable>machine-id</replaceable>/*.journal~</filename></term>
	<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
	<filename>/run/log/journal/<replaceable>machine-id</replaceable>/</filename>
	or
	<filename>/var/log/journal/<replaceable>machine-id</replaceable>/</filename>
	with the <literal>.journal</literal> suffix. If the daemon is
	stopped uncleanly, or if the files are found to be corrupted,
	they are renamed using the <literal>.journal~</literal>
	suffix, and <command>systemd-journald</command> starts writing
	to a new file. <filename>/run</filename> is used when
	<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>

	<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>
	<term><filename>/dev/kmsg</filename></term>
	<term><filename>/dev/log</filename></term>
	<term><filename>/run/systemd/journal/dev-log</filename></term>
	<term><filename>/run/systemd/journal/socket</filename></term>
	<term><filename>/run/systemd/journal/stdout</filename></term>

	<listitem><para>Sockets and other paths that
	<command>systemd-journald</command> will listen on that are
	visible in the file system. In addition to these, journald can
	listen for audit events using netlink.</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>,
	<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>3</manvolnum></citerefentry>,
	<command>pydoc systemd.journal</command>
	</para>
	</refsect1>

	</refentry>