path: root/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 General Public License as published by
  the Free Software Foundation; either version 2 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
  General Public License for more details.

  You should have received a copy of the GNU 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
                ASCII strings, and binary formatting is used only
                where formatting as ASCII makes little sense. New
                fields may be freely defined by applications, but a
                few fields have special meaning. All fields with
                special meaning are optional.</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>
                        <varlistentry>
                                <term>MESSAGE=</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 not translated,
                                        and is not supposed to be
                                        parsed for meta data.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term>MESSAGE_ID=</term>
                                <listitem>
                                        <para>A 128bit message
                                        identifier ID for recognizing
                                        certain message types, if this
                                        is desirable. This should
                                        contain a 128bit id formatted
                                        as 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
                                        --new-id</command>.</para>
                                </listitem>
                        </varlistentry>

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

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

                        <varlistentry>
                                <term>SYSLOG_FACILITY=</term>
                                <term>SYSLOG_IDENTIFIER=</term>
                                <term>SYSLOG_PID=</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>
                        <varlistentry>
                                <term>_PID=</term>
                                <term>_UID=</term>
                                <term>_GID=</term>
                                <listitem>
                                        <para>The process, user and
                                        group ID of the process the
                                        journal entry originates from
                                        formatted as decimal
                                        string.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term>_COMM=</term>
                                <term>_EXE=</term>
                                <term>_CMDLINE=</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>_AUDIT_SESSION=</term>
                                <term>_AUDIT_LOGINUID=</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>_SYSTEMD_CGROUP=</term>
                                <term>_SYSTEMD_SESSION=</term>
                                <term>_SYSTEMD_UNIT=</term>
                                <term>_SYSTEMD_OWNER_UID=</term>

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

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

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

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

                        <varlistentry>
                                <term>_MACHINE_ID=</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>_HOSTNAME=</term>
                                <listitem>
                                        <para>The name of the
                                        originating host.</para>
                                </listitem>
                        </varlistentry>
                </variablelist>
        </refsect1>

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

                <para>During serialization into external formats the
                addresses of journal entries are serialized into
                fields prefixed with double underscores. Note that
                these aren't proper fields when stored in the journal,
                but addressing meta data of entries.</para>

                <variablelist>
                        <varlistentry>
                                <term>__CURSOR=</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>__REALTIME_TIMESTAMP=</term>
                                <listitem>
                                        <para>The wallclock time
                                        (CLOCK_REALTIME) at the point
                                        in time the entry was received
                                        by the journal. 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>__MONOTONIC_TIMESTAMP=</term>
                                <listitem>
                                        <para>The monotonic time
                                        (CLOCK_MONOTONIC) at the point
                                        in time the entry was received
                                        by the journal. To be useful
                                        as an address for the entry
                                        this should be combined with
                                        with 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>
                  </para>
        </refsect1>

</refentry>