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

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 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   Copyright 2010 Lennart Poettering

   systemd is free software; you can redistribute it and/or modify it
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   (at your option) any later version.

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 <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-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 libc
       <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>4</manvolnum></citerefentry></para></listitem>

       <listitem><para>Standard output and standard error of system
       services</para></listitem>

       <listitem><para>Audit records, via the 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. 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>

     <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>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 her/him to read
     the journal files.</para>

     <para>By default, each logged in user will get her/his 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></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>4</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">

	<!--
	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-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 libc
	<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>4</manvolnum></citerefentry></para></listitem>

	<listitem><para>Standard output and standard error of system
	services</para></listitem>

	<listitem><para>Audit records, via the 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. 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>

	<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>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 her/him to read
	the journal files.</para>

	<para>By default, each logged in user will get her/his 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></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>4</manvolnum></citerefentry>,
	<command>pydoc systemd.journal</command>
	</para>
	</refsect1>

	</refentry>