[thirdparty/systemd.git] / man / systemd.journal-fields.xml

<?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.journal-fields">

        <refentryinfo>
                <title>systemd.journal-fields</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.journal-fields</refentrytitle>
                <manvolnum>7</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>systemd.journal-fields</refname>
                <refpurpose>Special journal fields</refpurpose>
        </refnamediv>

        <refsect1>
                <title>Description</title>

                <para>Entries in the journal resemble an environment
                block in their syntax, however with fields that can
                include binary data. Primarily, fields are formatted
                UTF-8 text strings, and binary formatting is used only
                where formatting as UTF-8 text strings makes little
                sense. New fields may freely be defined by
                applications, but a few fields have special
                meaning. All fields with special meanings are
                optional. In some cases fields may appear more than
                once per entry.</para>
        </refsect1>

        <refsect1>
                <title>User Journal Fields</title>

                <para>User fields are fields that are directly passed
                from clients and stored in the journal.</para>

                <variablelist class='journal-directives'>
                        <varlistentry>
                                <term><varname>MESSAGE=</varname></term>
                                <listitem>
                                        <para>The human-readable
                                        message string for this
                                        entry. This is supposed to be
                                        the primary text shown to the
                                        user. It is usually not
                                        translated (but might be in
                                        some cases), and is not
                                        supposed to be parsed for meta
                                        data.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>MESSAGE_ID=</varname></term>
                                <listitem>
                                        <para>A 128-bit message
                                        identifier ID for recognizing
                                        certain message types, if this
                                        is desirable. This should
                                        contain a 128-bit ID formatted
                                        as a lower-case hexadecimal
                                        string, without any separating
                                        dashes or suchlike. This is
                                        recommended to be a
                                        UUID-compatible ID, but this is not
                                        enforced, and formatted
                                        differently. Developers can
                                        generate a new ID for this
                                        purpose with <command>journalctl
                                        <option>--new-id</option></command>.
                                        </para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>PRIORITY=</varname></term>
                                <listitem>
                                        <para>A priority value between
                                        0 (<literal>emerg</literal>)
                                        and 7
                                        (<literal>debug</literal>)
                                        formatted as a decimal
                                        string. This field is
                                        compatible with syslog's
                                        priority concept.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>CODE_FILE=</varname></term>
                                <term><varname>CODE_LINE=</varname></term>
                                <term><varname>CODE_FUNC=</varname></term>
                                <listitem>
                                        <para>The code location
                                        generating this message, if
                                        known. Contains the source
                                        filename, the line number and
                                        the function name.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>ERRNO=</varname></term>
                                <listitem>
                                        <para>The low-level Unix error
                                        number causing this entry, if
                                        any. Contains the numeric
                                        value of
                                        <citerefentry><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                                        formatted as a decimal
                                        string.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>SYSLOG_FACILITY=</varname></term>
                                <term><varname>SYSLOG_IDENTIFIER=</varname></term>
                                <term><varname>SYSLOG_PID=</varname></term>
                                <listitem>
                                        <para>Syslog compatibility
                                        fields containing the facility
                                        (formatted as decimal string),
                                        the identifier string
                                        (i.e. "tag"), and the client
                                        PID.</para>
                                </listitem>

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

        <refsect1>
                <title>Trusted Journal Fields</title>

                <para>Fields prefixed with an underscore are trusted
                fields, i.e. fields that are implicitly added by the
                journal and cannot be altered by client code.</para>

                <variablelist class='journal-directives'>
                        <varlistentry>
                                <term><varname>_PID=</varname></term>
                                <term><varname>_UID=</varname></term>
                                <term><varname>_GID=</varname></term>
                                <listitem>
                                        <para>The process, user and
                                        group ID of the process the
                                        journal entry originates from
                                        formatted as a decimal
                                        string.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>_COMM=</varname></term>
                                <term><varname>_EXE=</varname></term>
                                <term><varname>_CMDLINE=</varname></term>
                                <listitem>
                                        <para>The name, the executable
                                        path and the command line of
                                        the process the journal entry
                                        originates from.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>_CAP_EFFECTIVE=</varname></term>
                                <listitem>
                                        <para>The effective <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> of
                                        the process the journal entry
                                        originates from.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>_AUDIT_SESSION=</varname></term>
                                <term><varname>_AUDIT_LOGINUID=</varname></term>
                                <listitem>
                                        <para>The session and login
                                        UID of the process the journal
                                        entry originates from, as
                                        maintained by the kernel audit
                                        subsystem.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>_SYSTEMD_CGROUP=</varname></term>
                                <term><varname>_SYSTEMD_SESSION=</varname></term>
                                <term><varname>_SYSTEMD_UNIT=</varname></term>
                                <term><varname>_SYSTEMD_USER_UNIT=</varname></term>
                                <term><varname>_SYSTEMD_OWNER_UID=</varname></term>
                                <term><varname>_SYSTEMD_SLICE=</varname></term>

                                <listitem>
                                        <para>The control group path
                                        in the systemd hierarchy, the
                                        systemd session ID (if any),
                                        the systemd unit name (if
                                        any), the systemd user session
                                        unit name (if any), the owner
                                        UID of the systemd session (if
                                        any) and the systemd slice
                                        unit of the process the
                                        journal entry originates
                                        from.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>_SELINUX_CONTEXT=</varname></term>
                                <listitem>
                                        <para>The SELinux security
                                        context of the process the
                                        journal entry originates
                                        from.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>_SOURCE_REALTIME_TIMESTAMP=</varname></term>
                                <listitem>
                                        <para>The earliest trusted
                                        timestamp of the message, if
                                        any is known that is different
                                        from the reception time of the
                                        journal. This is the time in
                                        microseconds since the epoch UTC,
                                        formatted as a decimal
                                        string.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>_BOOT_ID=</varname></term>
                                <listitem>
                                        <para>The kernel boot ID for
                                        the boot the message was
                                        generated in, formatted as
                                        a 128-bit hexadecimal
                                        string.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>_MACHINE_ID=</varname></term>
                                <listitem>
                                        <para>The machine ID of the
                                        originating host, as available
                                        in
                                        <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>_HOSTNAME=</varname></term>
                                <listitem>
                                        <para>The name of the
                                        originating host.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>_TRANSPORT=</varname></term>
                                <listitem>
                                        <para>How the entry was
                                        received by the journal
                                        service. Valid transports are:
                                        </para>
                                        <variablelist>
                                                <varlistentry>
                                                        <term>
                                                                <option>driver</option>
                                                        </term>
                                                        <listitem>
                                                                <para>for
                                                                internally
                                                                generated
                                                                messages
                                                                </para>
                                                        </listitem>
                                                </varlistentry>

                                                <varlistentry>
                                                        <term>
                                                                <option>syslog</option>
                                                        </term>
                                                        <listitem>
                                                                <para>for those
                                                                received via the
                                                                local syslog
                                                                socket with the
                                                                syslog protocol
                                                                </para>
                                                        </listitem>
                                                </varlistentry>

                                                <varlistentry>
                                                        <term>
                                                                <option>journal</option>
                                                        </term>
                                                        <listitem>
                                                                <para>for those
                                                                received via the
                                                                native journal
                                                                protocol
                                                                </para>
                                                        </listitem>
                                                </varlistentry>

                                                <varlistentry>
                                                        <term>
                                                                <option>stdout</option>
                                                        </term>
                                                        <listitem>
                                                                <para>for those
                                                                read from a
                                                                service's
                                                                standard output
                                                                or error output
                                                                </para>
                                                        </listitem>
                                                </varlistentry>

                                                <varlistentry>
                                                        <term>
                                                                <option>kernel</option>
                                                        </term>
                                                        <listitem>
                                                                <para>for those
                                                                read from the
                                                                kernel
                                                                </para>
                                                        </listitem>
                                                </varlistentry>
                                        </variablelist>
                                </listitem>
                        </varlistentry>
                </variablelist>
        </refsect1>

        <refsect1>
                <title>Kernel Journal Fields</title>

                <para>Kernel fields are fields that are used by
                messages originating in the kernel and stored in the
                journal.</para>

                <variablelist class='journal-directives'>
                        <varlistentry>
                                <term><varname>_KERNEL_DEVICE=</varname></term>
                                <listitem>
                                        <para>The kernel device
                                        name. If the entry is
                                        associated to a block device,
                                        the major and minor of the
                                        device node, separated by <literal>:</literal>
                                        and prefixed by <literal>b</literal>. Similar
                                        for character devices, but
                                        prefixed by <literal>c</literal>. For network
                                        devices the interface index,
                                        prefixed by <literal>n</literal>. For all other
                                        devices <literal>+</literal> followed by the
                                        subsystem name, followed by
                                        <literal>:</literal>, followed by the kernel
                                        device name.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><varname>_KERNEL_SUBSYSTEM=</varname></term>
                                <listitem>
                                        <para>The kernel subsystem name.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><varname>_UDEV_SYSNAME=</varname></term>
                                <listitem>
                                        <para>The kernel device name
                                        as it shows up in the device
                                        tree below
                                        <filename>/sys</filename>.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><varname>_UDEV_DEVNODE=</varname></term>
                                <listitem>
                                        <para>The device node path of
                                        this device in
                                        <filename>/dev</filename>.</para>
                                </listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><varname>_UDEV_DEVLINK=</varname></term>
                                <listitem>
                                        <para>Additional symlink names
                                        pointing to the device node in
                                        <filename>/dev</filename>. This
                                        field is frequently set more
                                        than once per entry.</para>
                                </listitem>
                        </varlistentry>
                </variablelist>
        </refsect1>

        <refsect1>
                <title>Fields to log on behalf of a different program</title>

                <para>Fields in this section are used by programs
                to specify that they are logging on behalf of another
                program or unit.
                </para>

                <para>Fields used by the <command>systemd-coredump</command>
                coredump kernel helper:
                </para>

                <variablelist class='journal-directives'>
                        <varlistentry>
                                <term><varname>COREDUMP_UNIT=</varname></term>
                                <term><varname>COREDUMP_USER_UNIT=</varname></term>
                                <listitem>
                                        <para>Used to annotate
                                        messages containing coredumps from
                                        system and session units.
                                        See
                                        <citerefentry><refentrytitle>systemd-coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
                                        </para>
                                </listitem>
                        </varlistentry>
                </variablelist>

                <para>Priviledged programs (currently UID 0) may
                attach <varname>OBJECT_PID=</varname> to a
                message. This will instruct
                <command>systemd-journald</command> to attach
                additional fields on behalf of the caller:</para>

                <variablelist class='journal-directives'>
                        <varlistentry>
                                <term><varname>OBJECT_PID=<replaceable>PID</replaceable></varname></term>
                                <listitem>
                                        <para>PID of the program that this
                                        message pertains to.
                                        </para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>OBJECT_UID=</varname></term>
                                <term><varname>OBJECT_GID=</varname></term>
                                <term><varname>OBJECT_COMM=</varname></term>
                                <term><varname>OBJECT_EXE=</varname></term>
                                <term><varname>OBJECT_CMDLINE=</varname></term>
                                <term><varname>OBJECT_AUDIT_SESSION=</varname></term>
                                <term><varname>OBJECT_AUDIT_LOGINUID=</varname></term>
                                <term><varname>OBJECT_SYSTEMD_CGROUP=</varname></term>
                                <term><varname>OBJECT_SYSTEMD_SESSION=</varname></term>
                                <term><varname>OBJECT_SYSTEMD_OWNER_UID=</varname></term>
                                <term><varname>OBJECT_SYSTEMD_UNIT=</varname></term>
                                <term><varname>OBJECT_SYSTEMD_USER_UNIT=</varname></term>
                                <listitem>
                                        <para>These are additional fields added automatically
                                        by <command>systemd-journald</command>.
                                        Their meaning is the same as
                                        <varname>_UID=</varname>,
                                        <varname>_GID=</varname>,
                                        <varname>_COMM=</varname>,
                                        <varname>_EXE=</varname>,
                                        <varname>_CMDLINE=</varname>,
                                        <varname>_AUDIT_SESSION=</varname>,
                                        <varname>_AUDIT_LOGINUID=</varname>,
                                        <varname>_SYSTEMD_CGROUP=</varname>,
                                        <varname>_SYSTEMD_SESSION=</varname>,
                                        <varname>_SYSTEMD_UNIT=</varname>,
                                        <varname>_SYSTEMD_USER_UNIT=</varname>, and
                                        <varname>_SYSTEMD_OWNER_UID=</varname>
                                        as described above, except that the
                                        process identified by <replaceable>PID</replaceable>
                                        is described, instead of the process
                                        which logged the message.</para>
                                </listitem>
                        </varlistentry>
                </variablelist>


        </refsect1>

        <refsect1>
                <title>Address Fields</title>

                <para>During serialization into external formats, such
                as the <ulink
                url="http://www.freedesktop.org/wiki/Software/systemd/export">Journal
                Export Format</ulink> or the <ulink
                url="http://www.freedesktop.org/wiki/Software/systemd/json">Journal
                JSON Format</ulink>, the addresses of journal entries
                are serialized into fields prefixed with double
                underscores. Note that these are not proper fields when
                stored in the journal but for addressing meta data of
                entries. They cannot be written as part of structured
                log entries via calls such as
                <citerefentry><refentrytitle>sd_journal_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>. They
                may also not be used as matches for
                <citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry></para>

                <variablelist class='journal-directives'>
                        <varlistentry>
                                <term><varname>__CURSOR=</varname></term>
                                <listitem>
                                        <para>The cursor for the
                                        entry. A cursor is an opaque
                                        text string that uniquely
                                        describes the position of an
                                        entry in the journal and is
                                        portable across machines,
                                        platforms and journal files.
                                        </para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>__REALTIME_TIMESTAMP=</varname></term>
                                <listitem>
                                        <para>The wallclock time
                                        (<constant>CLOCK_REALTIME</constant>)
                                        at the point in time the entry
                                        was received by the journal,
                                        in microseconds since the epoch
                                        UTC, formatted as a decimal
                                        string. This has different
                                        properties from
                                        <literal>_SOURCE_REALTIME_TIMESTAMP=</literal>,
                                        as it is usually a bit later
                                        but more likely to be monotonic.
                                        </para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>__MONOTONIC_TIMESTAMP=</varname></term>
                                <listitem>
                                        <para>The monotonic time
                                        (<constant>CLOCK_MONOTONIC</constant>)
                                        at the point in time the entry
                                        was received by the journal in
                                        microseconds, formatted as a decimal
                                        string. To be useful as an
                                        address for the entry, this
                                        should be combined with with the
                                        boot ID in <literal>_BOOT_ID=</literal>.
                                        </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>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                          <citerefentry><refentrytitle>systemd-coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                          <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
                  </para>
        </refsect1>

</refentry>
Commit	Line	Data
ffa16db0 LP	1	<?xml version='1.0'?> <!---nxml--->
	2	<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
	3	"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
	4
	5	<!--
	6	This file is part of systemd.
	7
	8	Copyright 2010 Lennart Poettering
	9
	10	systemd is free software; you can redistribute it and/or modify it
5430f7f2 LP	11	under the terms of the GNU Lesser General Public License as published by
5430f7f2 LP	12	the Free Software Foundation; either version 2.1 of the License, or
ffa16db0 LP	13	(at your option) any later version.
	14
	15	systemd is distributed in the hope that it will be useful, but
	16	WITHOUT ANY WARRANTY; without even the implied warranty of
	17	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
5430f7f2	18	Lesser General Public License for more details.
ffa16db0	19
5430f7f2	20	You should have received a copy of the GNU Lesser General Public License
ffa16db0 LP	21	along with systemd; If not, see <http://www.gnu.org/licenses/>.
	22	-->
	23
	24	<refentry id="systemd.journal-fields">
	25
	26	<refentryinfo>
	27	<title>systemd.journal-fields</title>
	28	<productname>systemd</productname>
	29
	30	<authorgroup>
	31	<author>
	32	<contrib>Developer</contrib>
	33	<firstname>Lennart</firstname>
	34	<surname>Poettering</surname>
	35	<email>lennart@poettering.net</email>
	36	</author>
	37	</authorgroup>
	38	</refentryinfo>
	39
	40	<refmeta>
	41	<refentrytitle>systemd.journal-fields</refentrytitle>
	42	<manvolnum>7</manvolnum>
	43	</refmeta>
	44
	45	<refnamediv>
	46	<refname>systemd.journal-fields</refname>
	47	<refpurpose>Special journal fields</refpurpose>
	48	</refnamediv>
	49
	50	<refsect1>
	51	<title>Description</title>
	52
	53	<para>Entries in the journal resemble an environment
	54	block in their syntax, however with fields that can
	55	include binary data. Primarily, fields are formatted
a8eedf49 LP	56	UTF-8 text strings, and binary formatting is used only
	57	where formatting as UTF-8 text strings makes little
	58	sense. New fields may freely be defined by
	59	applications, but a few fields have special
	60	meaning. All fields with special meanings are
bdfb9e7f LP	61	optional. In some cases fields may appear more than
bdfb9e7f LP	62	once per entry.</para>
ffa16db0 LP	63	</refsect1>
	64
	65	<refsect1>
	66	<title>User Journal Fields</title>
	67
	68	<para>User fields are fields that are directly passed
	69	from clients and stored in the journal.</para>
	70
f6c2e28b	71	<variablelist class='journal-directives'>
ffa16db0	72	<varlistentry>
f6c2e28b	73	<term><varname>MESSAGE=</varname></term>
ffa16db0	74	<listitem>
e9dd9f95	75	<para>The human-readable
ffa16db0 LP	76	message string for this
	77	entry. This is supposed to be
	78	the primary text shown to the
33ba4c4b LP	79	user. It is usually not
	80	translated (but might be in
	81	some cases), and is not
	82	supposed to be parsed for meta
	83	data.</para>
ffa16db0 LP	84	</listitem>
	85	</varlistentry>
	86
	87	<varlistentry>
f6c2e28b	88	<term><varname>MESSAGE_ID=</varname></term>
ffa16db0	89	<listitem>
e9dd9f95	90	<para>A 128-bit message
ffa16db0 LP	91	identifier ID for recognizing
	92	certain message types, if this
	93	is desirable. This should
e9dd9f95 JSJ	94	contain a 128-bit ID formatted
e9dd9f95 JSJ	95	as a lower-case hexadecimal
ffa16db0 LP	96	string, without any separating
ffa16db0 LP	97	dashes or suchlike. This is
e9dd9f95 JSJ	98	recommended to be a
e9dd9f95 JSJ	99	UUID-compatible ID, but this is not
ffa16db0 LP	100	enforced, and formatted
	101	differently. Developers can
	102	generate a new ID for this
74d00578 ZJS	103	purpose with <command>journalctl
	104	<option>--new-id</option></command>.
	105	</para>
ffa16db0 LP	106	</listitem>
	107	</varlistentry>
	108
	109	<varlistentry>
f6c2e28b	110	<term><varname>PRIORITY=</varname></term>
ffa16db0 LP	111	<listitem>
	112	<para>A priority value between
	113	0 (<literal>emerg</literal>)
	114	and 7
	115	(<literal>debug</literal>)
e9dd9f95	116	formatted as a decimal
ffa16db0 LP	117	string. This field is
	118	compatible with syslog's
	119	priority concept.</para>
	120	</listitem>
	121	</varlistentry>
	122
	123	<varlistentry>
f6c2e28b ZJS	124	<term><varname>CODE_FILE=</varname></term>
	125	<term><varname>CODE_LINE=</varname></term>
	126	<term><varname>CODE_FUNC=</varname></term>
ffa16db0 LP	127	<listitem>
	128	<para>The code location
	129	generating this message, if
	130	known. Contains the source
e9dd9f95	131	filename, the line number and
ffa16db0 LP	132	the function name.</para>
	133	</listitem>
	134	</varlistentry>
18c7ed18 LP	135
18c7ed18 LP	136	<varlistentry>
f6c2e28b	137	<term><varname>ERRNO=</varname></term>
18c7ed18 LP	138	<listitem>
	139	<para>The low-level Unix error
	140	number causing this entry, if
	141	any. Contains the numeric
	142	value of
	143	<citerefentry><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
e9dd9f95	144	formatted as a decimal
18c7ed18 LP	145	string.</para>
	146	</listitem>
	147	</varlistentry>
ffa16db0 LP	148
ffa16db0 LP	149	<varlistentry>
f6c2e28b ZJS	150	<term><varname>SYSLOG_FACILITY=</varname></term>
	151	<term><varname>SYSLOG_IDENTIFIER=</varname></term>
	152	<term><varname>SYSLOG_PID=</varname></term>
ffa16db0 LP	153	<listitem>
	154	<para>Syslog compatibility
	155	fields containing the facility
	156	(formatted as decimal string),
	157	the identifier string
	158	(i.e. "tag"), and the client
	159	PID.</para>
	160	</listitem>
	161
	162	</varlistentry>
	163	</variablelist>
	164	</refsect1>
	165
	166	<refsect1>
	167	<title>Trusted Journal Fields</title>
	168
	169	<para>Fields prefixed with an underscore are trusted
	170	fields, i.e. fields that are implicitly added by the
	171	journal and cannot be altered by client code.</para>
	172
f6c2e28b	173	<variablelist class='journal-directives'>
ffa16db0	174	<varlistentry>
f6c2e28b ZJS	175	<term><varname>_PID=</varname></term>
	176	<term><varname>_UID=</varname></term>
	177	<term><varname>_GID=</varname></term>
ffa16db0 LP	178	<listitem>
	179	<para>The process, user and
	180	group ID of the process the
	181	journal entry originates from
e9dd9f95	182	formatted as a decimal
ffa16db0 LP	183	string.</para>
	184	</listitem>
	185	</varlistentry>
	186
	187	<varlistentry>
f6c2e28b ZJS	188	<term><varname>_COMM=</varname></term>
	189	<term><varname>_EXE=</varname></term>
	190	<term><varname>_CMDLINE=</varname></term>
ffa16db0 LP	191	<listitem>
	192	<para>The name, the executable
	193	path and the command line of
	194	the process the journal entry
	195	originates from.</para>
	196	</listitem>
	197	</varlistentry>
	198
3a832116 SL	199	<varlistentry>
	200	<term><varname>_CAP_EFFECTIVE=</varname></term>
	201	<listitem>
	202	<para>The effective <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> of
	203	the process the journal entry
	204	originates from.</para>
	205	</listitem>
	206	</varlistentry>
	207
ffa16db0	208	<varlistentry>
f6c2e28b ZJS	209	<term><varname>_AUDIT_SESSION=</varname></term>
f6c2e28b ZJS	210	<term><varname>_AUDIT_LOGINUID=</varname></term>
ffa16db0 LP	211	<listitem>
	212	<para>The session and login
	213	UID of the process the journal
	214	entry originates from, as
	215	maintained by the kernel audit
	216	subsystem.</para>
	217	</listitem>
	218	</varlistentry>
	219
	220	<varlistentry>
f6c2e28b ZJS	221	<term><varname>_SYSTEMD_CGROUP=</varname></term>
	222	<term><varname>_SYSTEMD_SESSION=</varname></term>
	223	<term><varname>_SYSTEMD_UNIT=</varname></term>
64abe9aa	224	<term><varname>_SYSTEMD_USER_UNIT=</varname></term>
f6c2e28b	225	<term><varname>_SYSTEMD_OWNER_UID=</varname></term>
0a244b8e	226	<term><varname>_SYSTEMD_SLICE=</varname></term>
ffa16db0 LP	227
ffa16db0 LP	228	<listitem>
0a244b8e LP	229	<para>The control group path
0a244b8e LP	230	in the systemd hierarchy, the
ffa16db0	231	systemd session ID (if any),
0a244b8e LP	232	the systemd unit name (if
	233	any), the systemd user session
	234	unit name (if any), the owner
	235	UID of the systemd session (if
	236	any) and the systemd slice
	237	unit of the process the
	238	journal entry originates
	239	from.</para>
ffa16db0 LP	240	</listitem>
	241	</varlistentry>
	242
	243	<varlistentry>
f6c2e28b	244	<term><varname>_SELINUX_CONTEXT=</varname></term>
ffa16db0 LP	245	<listitem>
	246	<para>The SELinux security
	247	context of the process the
	248	journal entry originates
	249	from.</para>
	250	</listitem>
	251	</varlistentry>
	252
	253	<varlistentry>
f6c2e28b	254	<term><varname>_SOURCE_REALTIME_TIMESTAMP=</varname></term>
ffa16db0 LP	255	<listitem>
	256	<para>The earliest trusted
	257	timestamp of the message, if
	258	any is known that is different
	259	from the reception time of the
41048afa	260	journal. This is the time in
e9dd9f95 JSJ	261	microseconds since the epoch UTC,
e9dd9f95 JSJ	262	formatted as a decimal
41048afa	263	string.</para>
ffa16db0 LP	264	</listitem>
	265	</varlistentry>
	266
	267	<varlistentry>
f6c2e28b	268	<term><varname>_BOOT_ID=</varname></term>
ffa16db0 LP	269	<listitem>
	270	<para>The kernel boot ID for
	271	the boot the message was
	272	generated in, formatted as
e9dd9f95	273	a 128-bit hexadecimal
ffa16db0 LP	274	string.</para>
	275	</listitem>
	276	</varlistentry>
	277
	278	<varlistentry>
f6c2e28b	279	<term><varname>_MACHINE_ID=</varname></term>
ffa16db0 LP	280	<listitem>
	281	<para>The machine ID of the
	282	originating host, as available
	283	in
	284	<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
	285	</listitem>
	286	</varlistentry>
	287
	288	<varlistentry>
f6c2e28b	289	<term><varname>_HOSTNAME=</varname></term>
ffa16db0 LP	290	<listitem>
	291	<para>The name of the
	292	originating host.</para>
	293	</listitem>
	294	</varlistentry>
6bc3bf5b LP	295
6bc3bf5b LP	296	<varlistentry>
f6c2e28b	297	<term><varname>_TRANSPORT=</varname></term>
6bc3bf5b LP	298	<listitem>
	299	<para>How the entry was
	300	received by the journal
3ae83f98	301	service. Valid transports are:
6bc3bf5b	302	</para>
3ae83f98 JSJ	303	<variablelist>
	304	<varlistentry>
	305	<term>
	306	<option>driver</option>
	307	</term>
	308	<listitem>
	309	<para>for
	310	internally
	311	generated
	312	messages
	313	</para>
	314	</listitem>
	315	</varlistentry>
	316
	317	<varlistentry>
	318	<term>
	319	<option>syslog</option>
	320	</term>
	321	<listitem>
	322	<para>for those
	323	received via the
	324	local syslog
	325	socket with the
	326	syslog protocol
	327	</para>
	328	</listitem>
	329	</varlistentry>
	330
	331	<varlistentry>
	332	<term>
	333	<option>journal</option>
	334	</term>
	335	<listitem>
	336	<para>for those
	337	received via the
	338	native journal
	339	protocol
	340	</para>
	341	</listitem>
	342	</varlistentry>
	343
	344	<varlistentry>
	345	<term>
	346	<option>stdout</option>
	347	</term>
	348	<listitem>
	349	<para>for those
	350	read from a
	351	service's
	352	standard output
	353	or error output
	354	</para>
	355	</listitem>
	356	</varlistentry>
	357
	358	<varlistentry>
	359	<term>
	360	<option>kernel</option>
	361	</term>
	362	<listitem>
	363	<para>for those
	364	read from the
	365	kernel
	366	</para>
367	</listitem>
368	</varlistentry>
369	</variablelist>
6bc3bf5b LP	370	</listitem>
6bc3bf5b LP	371	</varlistentry>
ffa16db0 LP	372	</variablelist>
	373	</refsect1>
	374
6f7ea7df LP	375	<refsect1>
	376	<title>Kernel Journal Fields</title>
	377
	378	<para>Kernel fields are fields that are used by
	379	messages originating in the kernel and stored in the
	380	journal.</para>
	381
53057ef9	382	<variablelist class='journal-directives'>
6f7ea7df	383	<varlistentry>
53057ef9	384	<term><varname>_KERNEL_DEVICE=</varname></term>
6f7ea7df LP	385	<listitem>
	386	<para>The kernel device
	387	name. If the entry is
	388	associated to a block device,
	389	the major and minor of the
909f413d ZJS	390	device node, separated by <literal>:</literal>
909f413d ZJS	391	and prefixed by <literal>b</literal>. Similar
6f7ea7df	392	for character devices, but
909f413d	393	prefixed by <literal>c</literal>. For network
6f7ea7df	394	devices the interface index,
909f413d ZJS	395	prefixed by <literal>n</literal>. For all other
909f413d ZJS	396	devices <literal>+</literal> followed by the
6f7ea7df	397	subsystem name, followed by
909f413d	398	<literal>:</literal>, followed by the kernel
6f7ea7df LP	399	device name.</para>
	400	</listitem>
	401	</varlistentry>
	402	<varlistentry>
53057ef9	403	<term><varname>_KERNEL_SUBSYSTEM=</varname></term>
6f7ea7df LP	404	<listitem>
	405	<para>The kernel subsystem name.</para>
	406	</listitem>
	407	</varlistentry>
bdfb9e7f	408	<varlistentry>
53057ef9	409	<term><varname>_UDEV_SYSNAME=</varname></term>
bdfb9e7f LP	410	<listitem>
	411	<para>The kernel device name
	412	as it shows up in the device
	413	tree below
	414	<filename>/sys</filename>.</para>
	415	</listitem>
	416	</varlistentry>
	417	<varlistentry>
53057ef9	418	<term><varname>_UDEV_DEVNODE=</varname></term>
bdfb9e7f LP	419	<listitem>
	420	<para>The device node path of
	421	this device in
	422	<filename>/dev</filename>.</para>
	423	</listitem>
	424	</varlistentry>
	425	<varlistentry>
53057ef9	426	<term><varname>_UDEV_DEVLINK=</varname></term>
bdfb9e7f LP	427	<listitem>
	428	<para>Additional symlink names
	429	pointing to the device node in
	430	<filename>/dev</filename>. This
	431	field is frequently set more
	432	than once per entry.</para>
	433	</listitem>
	434	</varlistentry>
6f7ea7df LP	435	</variablelist>
	436	</refsect1>
	437
53057ef9	438	<refsect1>
5199cbe4 ZJS	439	<title>Fields to log on behalf of a different program</title>
	440
	441	<para>Fields in this section are used by programs
	442	to specify that they are logging on behalf of another
	443	program or unit.
	444	</para>
53057ef9 ZJS	445
53057ef9 ZJS	446	<para>Fields used by the <command>systemd-coredump</command>
5199cbe4	447	coredump kernel helper:
53057ef9 ZJS	448	</para>
	449
	450	<variablelist class='journal-directives'>
	451	<varlistentry>
	452	<term><varname>COREDUMP_UNIT=</varname></term>
	453	<term><varname>COREDUMP_USER_UNIT=</varname></term>
	454	<listitem>
	455	<para>Used to annotate
	456	messages containing coredumps from
	457	system and session units.
	458	See
	459	<citerefentry><refentrytitle>systemd-coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
	460	</para>
	461	</listitem>
	462	</varlistentry>
	463	</variablelist>
5199cbe4 ZJS	464
	465	<para>Priviledged programs (currently UID 0) may
	466	attach <varname>OBJECT_PID=</varname> to a
	467	message. This will instruct
	468	<command>systemd-journald</command> to attach
7b870f60	469	additional fields on behalf of the caller:</para>
5199cbe4 ZJS	470
	471	<variablelist class='journal-directives'>
	472	<varlistentry>
	473	<term><varname>OBJECT_PID=<replaceable>PID</replaceable></varname></term>
	474	<listitem>
	475	<para>PID of the program that this
	476	message pertains to.
	477	</para>
	478	</listitem>
	479	</varlistentry>
	480
	481	<varlistentry>
	482	<term><varname>OBJECT_UID=</varname></term>
	483	<term><varname>OBJECT_GID=</varname></term>
	484	<term><varname>OBJECT_COMM=</varname></term>
	485	<term><varname>OBJECT_EXE=</varname></term>
	486	<term><varname>OBJECT_CMDLINE=</varname></term>
	487	<term><varname>OBJECT_AUDIT_SESSION=</varname></term>
	488	<term><varname>OBJECT_AUDIT_LOGINUID=</varname></term>
	489	<term><varname>OBJECT_SYSTEMD_CGROUP=</varname></term>
	490	<term><varname>OBJECT_SYSTEMD_SESSION=</varname></term>
	491	<term><varname>OBJECT_SYSTEMD_OWNER_UID=</varname></term>
	492	<term><varname>OBJECT_SYSTEMD_UNIT=</varname></term>
	493	<term><varname>OBJECT_SYSTEMD_USER_UNIT=</varname></term>
	494	<listitem>
7b870f60	495	<para>These are additional fields added automatically
5199cbe4 ZJS	496	by <command>systemd-journald</command>.
	497	Their meaning is the same as
	498	<varname>_UID=</varname>,
	499	<varname>_GID=</varname>,
	500	<varname>_COMM=</varname>,
	501	<varname>_EXE=</varname>,
	502	<varname>_CMDLINE=</varname>,
	503	<varname>_AUDIT_SESSION=</varname>,
	504	<varname>_AUDIT_LOGINUID=</varname>,
	505	<varname>_SYSTEMD_CGROUP=</varname>,
	506	<varname>_SYSTEMD_SESSION=</varname>,
	507	<varname>_SYSTEMD_UNIT=</varname>,
	508	<varname>_SYSTEMD_USER_UNIT=</varname>, and
	509	<varname>_SYSTEMD_OWNER_UID=</varname>
7b870f60 JE	510	as described above, except that the
7b870f60 JE	511	process identified by <replaceable>PID</replaceable>
5199cbe4 ZJS	512	is described, instead of the process
	513	which logged the message.</para>
	514	</listitem>
	515	</varlistentry>
	516	</variablelist>
	517
	518
53057ef9 ZJS	519	</refsect1>
53057ef9 ZJS	520
ffa16db0 LP	521	<refsect1>
	522	<title>Address Fields</title>
	523
df688b23 LP	524	<para>During serialization into external formats, such
	525	as the <ulink
	526	url="http://www.freedesktop.org/wiki/Software/systemd/export">Journal
	527	Export Format</ulink> or the <ulink
	528	url="http://www.freedesktop.org/wiki/Software/systemd/json">Journal
	529	JSON Format</ulink>, the addresses of journal entries
	530	are serialized into fields prefixed with double
6b4991cf	531	underscores. Note that these are not proper fields when
e9dd9f95	532	stored in the journal but for addressing meta data of
df688b23 LP	533	entries. They cannot be written as part of structured
df688b23 LP	534	log entries via calls such as
cbdca852 LP	535	<citerefentry><refentrytitle>sd_journal_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>. They
	536	may also not be used as matches for
	537	<citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry></para>
ffa16db0	538
f6c2e28b	539	<variablelist class='journal-directives'>
ffa16db0	540	<varlistentry>
f6c2e28b	541	<term><varname>__CURSOR=</varname></term>
ffa16db0 LP	542	<listitem>
	543	<para>The cursor for the
	544	entry. A cursor is an opaque
	545	text string that uniquely
	546	describes the position of an
	547	entry in the journal and is
	548	portable across machines,
74d00578 ZJS	549	platforms and journal files.
74d00578 ZJS	550	</para>
ffa16db0 LP	551	</listitem>
	552	</varlistentry>
	553
	554	<varlistentry>
f6c2e28b	555	<term><varname>__REALTIME_TIMESTAMP=</varname></term>
ffa16db0 LP	556	<listitem>
ffa16db0 LP	557	<para>The wallclock time
74d00578 ZJS	558	(<constant>CLOCK_REALTIME</constant>)
	559	at the point in time the entry
	560	was received by the journal,
e9dd9f95 JSJ	561	in microseconds since the epoch
e9dd9f95 JSJ	562	UTC, formatted as a decimal
74d00578 ZJS	563	string. This has different
74d00578 ZJS	564	properties from
e9dd9f95	565	<literal>_SOURCE_REALTIME_TIMESTAMP=</literal>,
ffa16db0	566	as it is usually a bit later
74d00578 ZJS	567	but more likely to be monotonic.
74d00578 ZJS	568	</para>
ffa16db0 LP	569	</listitem>
	570	</varlistentry>
	571
	572	<varlistentry>
f6c2e28b	573	<term><varname>__MONOTONIC_TIMESTAMP=</varname></term>
ffa16db0 LP	574	<listitem>
ffa16db0 LP	575	<para>The monotonic time
74d00578 ZJS	576	(<constant>CLOCK_MONOTONIC</constant>)
	577	at the point in time the entry
	578	was received by the journal in
e9dd9f95	579	microseconds, formatted as a decimal
41048afa	580	string. To be useful as an
e9dd9f95 JSJ	581	address for the entry, this
e9dd9f95 JSJ	582	should be combined with with the
74d00578 ZJS	583	boot ID in <literal>_BOOT_ID=</literal>.
74d00578 ZJS	584	</para>
ffa16db0 LP	585	</listitem>
	586	</varlistentry>
	587	</variablelist>
	588	</refsect1>
	589
	590	<refsect1>
	591	<title>See Also</title>
	592	<para>
	593	<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
	594	<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
a8eedf49	595	<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
9cc2c8b7	596	<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
53057ef9	597	<citerefentry><refentrytitle>systemd-coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
9cc2c8b7	598	<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
ffa16db0 LP	599	</para>
	600	</refsect1>
	601
	602	</refentry>