1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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6 This file is part of systemd.
8 Copyright 2010 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
11 under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 2.1 of the License, or
13 (at your option) any later version.
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18 Lesser General Public License for more details.
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24 <refentry id="systemd.journal-fields">
27 <title>systemd.journal-fields</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>systemd.journal-fields</refentrytitle>
42 <manvolnum>7</manvolnum>
46 <refname>systemd.journal-fields</refname>
47 <refpurpose>Special journal fields</refpurpose>
51 <title>Description</title>
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
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
61 optional. In some cases fields may appear more than
62 once per entry.</para>
66 <title>User Journal Fields</title>
68 <para>User fields are fields that are directly passed
69 from clients and stored in the journal.</para>
71 <variablelist class='journal-directives'>
73 <term><varname>MESSAGE=</varname></term>
75 <para>The human readable
76 message string for this
77 entry. This is supposed to be
78 the primary text shown to the
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
88 <term><varname>MESSAGE_ID=</varname></term>
90 <para>A 128bit message
91 identifier ID for recognizing
92 certain message types, if this
93 is desirable. This should
94 contain a 128bit id formatted
95 as lower-case hexadecimal
96 string, without any separating
97 dashes or suchlike. This is
98 recommended to be a UUID
99 compatible ID, but this is not
100 enforced, and formatted
101 differently. Developers can
102 generate a new ID for this
103 purpose with <command>journalctl
104 <option>--new-id</option></command>.
110 <term><varname>PRIORITY=</varname></term>
112 <para>A priority value between
113 0 (<literal>emerg</literal>)
115 (<literal>debug</literal>)
117 string. This field is
118 compatible with syslog's
119 priority concept.</para>
124 <term><varname>CODE_FILE=</varname></term>
125 <term><varname>CODE_LINE=</varname></term>
126 <term><varname>CODE_FUNC=</varname></term>
128 <para>The code location
129 generating this message, if
130 known. Contains the source
131 file name, the line number and
132 the function name.</para>
137 <term><varname>ERRNO=</varname></term>
139 <para>The low-level Unix error
140 number causing this entry, if
141 any. Contains the numeric
143 <citerefentry><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
150 <term><varname>SYSLOG_FACILITY=</varname></term>
151 <term><varname>SYSLOG_IDENTIFIER=</varname></term>
152 <term><varname>SYSLOG_PID=</varname></term>
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
167 <title>Trusted Journal Fields</title>
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>
173 <variablelist class='journal-directives'>
175 <term><varname>_PID=</varname></term>
176 <term><varname>_UID=</varname></term>
177 <term><varname>_GID=</varname></term>
179 <para>The process, user and
180 group ID of the process the
181 journal entry originates from
188 <term><varname>_COMM=</varname></term>
189 <term><varname>_EXE=</varname></term>
190 <term><varname>_CMDLINE=</varname></term>
192 <para>The name, the executable
193 path and the command line of
194 the process the journal entry
195 originates from.</para>
200 <term><varname>_AUDIT_SESSION=</varname></term>
201 <term><varname>_AUDIT_LOGINUID=</varname></term>
203 <para>The session and login
204 UID of the process the journal
205 entry originates from, as
206 maintained by the kernel audit
212 <term><varname>_SYSTEMD_CGROUP=</varname></term>
213 <term><varname>_SYSTEMD_SESSION=</varname></term>
214 <term><varname>_SYSTEMD_UNIT=</varname></term>
215 <term><varname>_SYSTEMD_USER_UNIT=</varname></term>
216 <term><varname>_SYSTEMD_OWNER_UID=</varname></term>
219 <para>The control group path in
220 the systemd hierarchy, the
221 systemd session ID (if any),
222 the systemd unit name (if any),
223 the systemd user session unit name (if any)
224 and the owner UID of the
225 systemd session (if any) of
226 the process the journal entry
227 originates from.</para>
232 <term><varname>_SELINUX_CONTEXT=</varname></term>
234 <para>The SELinux security
235 context of the process the
236 journal entry originates
242 <term><varname>_SOURCE_REALTIME_TIMESTAMP=</varname></term>
244 <para>The earliest trusted
245 timestamp of the message, if
246 any is known that is different
247 from the reception time of the
248 journal. This is the time in
249 usec since the epoch UTC
256 <term><varname>_BOOT_ID=</varname></term>
258 <para>The kernel boot ID for
259 the boot the message was
260 generated in, formatted as
267 <term><varname>_MACHINE_ID=</varname></term>
269 <para>The machine ID of the
270 originating host, as available
272 <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
277 <term><varname>_HOSTNAME=</varname></term>
279 <para>The name of the
280 originating host.</para>
285 <term><varname>_TRANSPORT=</varname></term>
287 <para>How the entry was
288 received by the journal
289 service. Valid transports are:
294 <option>driver</option>
307 <option>syslog</option>
321 <option>journal</option>
334 <option>stdout</option>
348 <option>kernel</option>
364 <title>Kernel Journal Fields</title>
366 <para>Kernel fields are fields that are used by
367 messages originating in the kernel and stored in the
370 <variablelist class='journal-directives'>
372 <term><varname>_KERNEL_DEVICE=</varname></term>
374 <para>The kernel device
375 name. If the entry is
376 associated to a block device,
377 the major and minor of the
378 device node, separated by <literal>:</literal>
379 and prefixed by <literal>b</literal>. Similar
380 for character devices, but
381 prefixed by <literal>c</literal>. For network
382 devices the interface index,
383 prefixed by <literal>n</literal>. For all other
384 devices <literal>+</literal> followed by the
385 subsystem name, followed by
386 <literal>:</literal>, followed by the kernel
391 <term><varname>_KERNEL_SUBSYSTEM=</varname></term>
393 <para>The kernel subsystem name.</para>
397 <term><varname>_UDEV_SYSNAME=</varname></term>
399 <para>The kernel device name
400 as it shows up in the device
402 <filename>/sys</filename>.</para>
406 <term><varname>_UDEV_DEVNODE=</varname></term>
408 <para>The device node path of
410 <filename>/dev</filename>.</para>
414 <term><varname>_UDEV_DEVLINK=</varname></term>
416 <para>Additional symlink names
417 pointing to the device node in
418 <filename>/dev</filename>. This
419 field is frequently set more
420 than once per entry.</para>
427 <title>Special Journal Fields</title>
429 <para>Fields used by the <command>systemd-coredump</command>
430 coredump kernel helper.
433 <variablelist class='journal-directives'>
435 <term><varname>COREDUMP_UNIT=</varname></term>
436 <term><varname>COREDUMP_USER_UNIT=</varname></term>
438 <para>Used to annotate
439 messages containing coredumps from
440 system and session units.
442 <citerefentry><refentrytitle>systemd-coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
450 <title>Address Fields</title>
452 <para>During serialization into external formats, such
454 url="http://www.freedesktop.org/wiki/Software/systemd/export">Journal
455 Export Format</ulink> or the <ulink
456 url="http://www.freedesktop.org/wiki/Software/systemd/json">Journal
457 JSON Format</ulink>, the addresses of journal entries
458 are serialized into fields prefixed with double
459 underscores. Note that these aren't proper fields when
460 stored in the journal, but addressing meta data of
461 entries. They cannot be written as part of structured
462 log entries via calls such as
463 <citerefentry><refentrytitle>sd_journal_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>. They
464 may also not be used as matches for
465 <citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry></para>
467 <variablelist class='journal-directives'>
469 <term><varname>__CURSOR=</varname></term>
471 <para>The cursor for the
472 entry. A cursor is an opaque
473 text string that uniquely
474 describes the position of an
475 entry in the journal and is
476 portable across machines,
477 platforms and journal files.
483 <term><varname>__REALTIME_TIMESTAMP=</varname></term>
485 <para>The wallclock time
486 (<constant>CLOCK_REALTIME</constant>)
487 at the point in time the entry
488 was received by the journal,
489 in usec since the epoch UTC
491 string. This has different
493 <literal>_SOURCE_REALTIME_TIMESTAMP=</literal>
494 as it is usually a bit later
495 but more likely to be monotonic.
501 <term><varname>__MONOTONIC_TIMESTAMP=</varname></term>
503 <para>The monotonic time
504 (<constant>CLOCK_MONOTONIC</constant>)
505 at the point in time the entry
506 was received by the journal in
507 usec formatted as decimal
508 string. To be useful as an
509 address for the entry this
510 should be combined with with
511 boot ID in <literal>_BOOT_ID=</literal>.
519 <title>See Also</title>
521 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
522 <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
523 <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
524 <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
525 <citerefentry><refentrytitle>systemd-coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
526 <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>