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ffa16db0 | 1 | <?xml version='1.0'?> <!--*-nxml-*--> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
0307f791 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1+ --> |
ffa16db0 LP |
5 | |
6 | <refentry id="systemd.journal-fields"> | |
7 | ||
798d3a52 ZJS |
8 | <refentryinfo> |
9 | <title>systemd.journal-fields</title> | |
10 | <productname>systemd</productname> | |
798d3a52 ZJS |
11 | </refentryinfo> |
12 | ||
13 | <refmeta> | |
14 | <refentrytitle>systemd.journal-fields</refentrytitle> | |
15 | <manvolnum>7</manvolnum> | |
16 | </refmeta> | |
17 | ||
18 | <refnamediv> | |
19 | <refname>systemd.journal-fields</refname> | |
20 | <refpurpose>Special journal fields</refpurpose> | |
21 | </refnamediv> | |
22 | ||
23 | <refsect1> | |
24 | <title>Description</title> | |
25 | ||
5a5bd9f7 LP |
26 | <para>Entries in the journal (as written by |
27 | <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>) | |
28 | resemble a UNIX process environment block in syntax but with fields that may include binary data. | |
29 | Primarily, fields are formatted UTF-8 text strings, and binary encoding is used only where formatting as | |
30 | UTF-8 text strings makes little sense. New fields may freely be defined by applications, but a few fields | |
31 | have special meanings. All fields with special meanings are optional. In some cases, fields may appear | |
32 | more than once per entry.</para> | |
798d3a52 ZJS |
33 | </refsect1> |
34 | ||
35 | <refsect1> | |
36 | <title>User Journal Fields</title> | |
37 | ||
38 | <para>User fields are fields that are directly passed from clients | |
39 | and stored in the journal.</para> | |
40 | ||
41 | <variablelist class='journal-directives'> | |
42 | <varlistentry> | |
43 | <term><varname>MESSAGE=</varname></term> | |
44 | <listitem> | |
45 | <para>The human-readable message string for this entry. This | |
46 | is supposed to be the primary text shown to the user. It is | |
47 | usually not translated (but might be in some cases), and is | |
dd2b607b | 48 | not supposed to be parsed for metadata.</para> |
798d3a52 ZJS |
49 | </listitem> |
50 | </varlistentry> | |
51 | ||
52 | <varlistentry> | |
53 | <term><varname>MESSAGE_ID=</varname></term> | |
54 | <listitem> | |
b9d016d6 LP |
55 | <para>A 128-bit message identifier ID for recognizing certain message types, if this is desirable. This |
56 | should contain a 128-bit ID formatted as a lower-case hexadecimal string, without any separating dashes or | |
57 | suchlike. This is recommended to be a UUID-compatible ID, but this is not enforced, and formatted | |
58 | differently. Developers can generate a new ID for this purpose with <command>systemd-id128 new</command>. | |
798d3a52 ZJS |
59 | </para> |
60 | </listitem> | |
61 | </varlistentry> | |
62 | ||
63 | <varlistentry> | |
64 | <term><varname>PRIORITY=</varname></term> | |
65 | <listitem> | |
66 | <para>A priority value between 0 (<literal>emerg</literal>) | |
67 | and 7 (<literal>debug</literal>) formatted as a decimal | |
68 | string. This field is compatible with syslog's priority | |
69 | concept.</para> | |
70 | </listitem> | |
71 | </varlistentry> | |
72 | ||
73 | <varlistentry> | |
74 | <term><varname>CODE_FILE=</varname></term> | |
75 | <term><varname>CODE_LINE=</varname></term> | |
76 | <term><varname>CODE_FUNC=</varname></term> | |
77 | <listitem> | |
78 | <para>The code location generating this message, if known. | |
79 | Contains the source filename, the line number and the | |
80 | function name.</para> | |
81 | </listitem> | |
82 | </varlistentry> | |
83 | ||
84 | <varlistentry> | |
85 | <term><varname>ERRNO=</varname></term> | |
86 | <listitem> | |
87 | <para>The low-level Unix error number causing this entry, if | |
88 | any. Contains the numeric value of | |
89 | <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
90 | formatted as a decimal string.</para> | |
91 | </listitem> | |
92 | </varlistentry> | |
93 | ||
ef886390 AZ |
94 | <varlistentry> |
95 | <term><varname>INVOCATION_ID=</varname></term> | |
96 | <term><varname>USER_INVOCATION_ID=</varname></term> | |
97 | <listitem> | |
98 | <para>A randomized, unique 128-bit ID identifying each runtime cycle of the unit. This is different from | |
99 | <varname>_SYSTEMD_INVOCATION_ID</varname> in that it is only used for messages coming from systemd code | |
100 | (e.g. logs from the system/user manager or from forked processes performing systemd-related setup).</para> | |
101 | </listitem> | |
102 | </varlistentry> | |
103 | ||
798d3a52 ZJS |
104 | <varlistentry> |
105 | <term><varname>SYSLOG_FACILITY=</varname></term> | |
106 | <term><varname>SYSLOG_IDENTIFIER=</varname></term> | |
107 | <term><varname>SYSLOG_PID=</varname></term> | |
7c30c3c4 | 108 | <term><varname>SYSLOG_TIMESTAMP=</varname></term> |
798d3a52 | 109 | <listitem> |
7c30c3c4 ZJS |
110 | <para>Syslog compatibility fields containing the facility (formatted as |
111 | decimal string), the identifier string (i.e. "tag"), the client PID, and | |
112 | the timestamp as specified in the original datagram. (Note that the tag is | |
113 | usually derived from glibc's | |
114 | <varname>program_invocation_short_name</varname> variable, see | |
3ba3a79d | 115 | <citerefentry project='die-net'><refentrytitle>program_invocation_short_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>.)</para> |
63ea8032 JS |
116 | <para>Note that the journal service does not validate the values of any structured |
117 | journal fields whose name is not prefixed with an underscore, and this includes any | |
118 | syslog related fields such as these. Hence, applications that supply a facility, PID, | |
119 | or log level are expected to do so properly formatted, i.e. as numeric integers formatted | |
120 | as decimal strings.</para> | |
798d3a52 | 121 | </listitem> |
df8701a3 | 122 | </varlistentry> |
798d3a52 | 123 | |
df8701a3 ZJS |
124 | <varlistentry> |
125 | <term><varname>SYSLOG_RAW=</varname></term> | |
126 | <listitem> | |
127 | <para>The original contents of the syslog line as received in the syslog | |
128 | datagram. This field is only included if the <varname>MESSAGE=</varname> | |
7c30c3c4 ZJS |
129 | field was modified compared to the original payload or the timestamp could |
130 | not be located properly and is not included in | |
131 | <varname>SYSLOG_TIMESTAMP=</varname>. Message truncation occurs when when | |
132 | the message contains leading or trailing whitespace (trailing and leading | |
df8701a3 ZJS |
133 | whitespace is stripped), or it contains an embedded |
134 | <constant>NUL</constant> byte (the <constant>NUL</constant> byte and | |
135 | anything after it is not included). Thus, the original syslog line is | |
136 | either stored as <varname>SYSLOG_RAW=</varname> or it can be recreated | |
7c30c3c4 ZJS |
137 | based on the stored priority and facility, timestamp, identifier, and the |
138 | message payload in <varname>MESSAGE=</varname>. | |
139 | </para> | |
df8701a3 | 140 | </listitem> |
798d3a52 | 141 | </varlistentry> |
dd587c3a LP |
142 | |
143 | <varlistentry> | |
144 | <term><varname>DOCUMENTATION=</varname></term> | |
145 | <listitem> | |
146 | <para>A documentation URL with further information about the topic of the log message. Tools such | |
147 | as <command>journalctl</command> will include a hyperlink to an URL specified this way in their | |
148 | output. Should be a <literal>http://</literal>, <literal>https://</literal>, | |
149 | <literal>file:/</literal>, <literal>man:</literal> or <literal>info:</literal> URL.</para> | |
150 | </listitem> | |
151 | </varlistentry> | |
798d3a52 ZJS |
152 | </variablelist> |
153 | </refsect1> | |
154 | ||
155 | <refsect1> | |
156 | <title>Trusted Journal Fields</title> | |
157 | ||
158 | <para>Fields prefixed with an underscore are trusted fields, i.e. | |
159 | fields that are implicitly added by the journal and cannot be | |
160 | altered by client code.</para> | |
161 | ||
162 | <variablelist class='journal-directives'> | |
163 | <varlistentry> | |
164 | <term><varname>_PID=</varname></term> | |
165 | <term><varname>_UID=</varname></term> | |
166 | <term><varname>_GID=</varname></term> | |
167 | <listitem> | |
168 | <para>The process, user, and group ID of the process the | |
169 | journal entry originates from formatted as a decimal | |
a96f668e MK |
170 | string. Note that entries obtained via <literal>stdout</literal> or |
171 | <literal>stderr</literal> of forked processes will contain credentials valid for a parent | |
172 | process (that initiated the connection to <command>systemd-journald</command>).</para> | |
798d3a52 ZJS |
173 | </listitem> |
174 | </varlistentry> | |
175 | ||
176 | <varlistentry> | |
177 | <term><varname>_COMM=</varname></term> | |
178 | <term><varname>_EXE=</varname></term> | |
179 | <term><varname>_CMDLINE=</varname></term> | |
180 | <listitem> | |
181 | <para>The name, the executable path, and the command line of | |
182 | the process the journal entry originates from.</para> | |
183 | </listitem> | |
184 | </varlistentry> | |
185 | ||
186 | <varlistentry> | |
187 | <term><varname>_CAP_EFFECTIVE=</varname></term> | |
188 | <listitem> | |
189 | <para>The effective | |
190 | <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
191 | of the process the journal entry originates from.</para> | |
192 | </listitem> | |
193 | </varlistentry> | |
194 | ||
195 | <varlistentry> | |
196 | <term><varname>_AUDIT_SESSION=</varname></term> | |
197 | <term><varname>_AUDIT_LOGINUID=</varname></term> | |
198 | <listitem> | |
199 | <para>The session and login UID of the process the journal | |
200 | entry originates from, as maintained by the kernel audit | |
201 | subsystem.</para> | |
202 | </listitem> | |
203 | </varlistentry> | |
204 | ||
205 | <varlistentry> | |
206 | <term><varname>_SYSTEMD_CGROUP=</varname></term> | |
fa93fe9c | 207 | <term><varname>_SYSTEMD_SLICE=</varname></term> |
798d3a52 ZJS |
208 | <term><varname>_SYSTEMD_UNIT=</varname></term> |
209 | <term><varname>_SYSTEMD_USER_UNIT=</varname></term> | |
0e4a4f56 | 210 | <term><varname>_SYSTEMD_USER_SLICE=</varname></term> |
fa93fe9c | 211 | <term><varname>_SYSTEMD_SESSION=</varname></term> |
798d3a52 | 212 | <term><varname>_SYSTEMD_OWNER_UID=</varname></term> |
798d3a52 ZJS |
213 | |
214 | <listitem> | |
215 | <para>The control group path in the systemd hierarchy, the | |
fa93fe9c AJ |
216 | the systemd slice unit name, the systemd unit name, the |
217 | unit name in the systemd user manager (if any), the systemd | |
218 | session ID (if any), and the owner UID of the systemd user | |
219 | unit or systemd session (if any) of the process the journal | |
220 | entry originates from.</para> | |
798d3a52 ZJS |
221 | </listitem> |
222 | </varlistentry> | |
223 | ||
224 | <varlistentry> | |
225 | <term><varname>_SELINUX_CONTEXT=</varname></term> | |
226 | <listitem> | |
227 | <para>The SELinux security context (label) of the process | |
228 | the journal entry originates from.</para> | |
229 | </listitem> | |
230 | </varlistentry> | |
231 | ||
232 | <varlistentry> | |
233 | <term><varname>_SOURCE_REALTIME_TIMESTAMP=</varname></term> | |
234 | <listitem> | |
235 | <para>The earliest trusted timestamp of the message, if any | |
236 | is known that is different from the reception time of the | |
237 | journal. This is the time in microseconds since the epoch | |
238 | UTC, formatted as a decimal string.</para> | |
239 | </listitem> | |
240 | </varlistentry> | |
241 | ||
242 | <varlistentry> | |
243 | <term><varname>_BOOT_ID=</varname></term> | |
244 | <listitem> | |
245 | <para>The kernel boot ID for the boot the message was | |
246 | generated in, formatted as a 128-bit hexadecimal | |
247 | string.</para> | |
248 | </listitem> | |
249 | </varlistentry> | |
250 | ||
251 | <varlistentry> | |
252 | <term><varname>_MACHINE_ID=</varname></term> | |
253 | <listitem> | |
254 | <para>The machine ID of the originating host, as available | |
255 | in | |
256 | <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> | |
257 | </listitem> | |
258 | </varlistentry> | |
259 | ||
dbb1d5cf LW |
260 | <varlistentry> |
261 | <term><varname>_SYSTEMD_INVOCATION_ID=</varname></term> | |
262 | <listitem> | |
263 | <para>The invocation ID for the runtime cycle of the unit | |
264 | the message was generated in, as available to processes | |
265 | of the unit in <varname>$INVOCATION_ID</varname> (see | |
266 | <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>).</para> | |
267 | </listitem> | |
268 | </varlistentry> | |
269 | ||
798d3a52 ZJS |
270 | <varlistentry> |
271 | <term><varname>_HOSTNAME=</varname></term> | |
272 | <listitem> | |
273 | <para>The name of the originating host.</para> | |
274 | </listitem> | |
275 | </varlistentry> | |
276 | ||
277 | <varlistentry> | |
278 | <term><varname>_TRANSPORT=</varname></term> | |
279 | <listitem> | |
280 | <para>How the entry was received by the journal service. | |
281 | Valid transports are: | |
282 | </para> | |
283 | <variablelist> | |
8983e16a EV |
284 | <varlistentry> |
285 | <term> | |
286 | <option>audit</option> | |
287 | </term> | |
288 | <listitem> | |
289 | <para>for those read from the kernel audit subsystem | |
290 | </para> | |
291 | </listitem> | |
292 | </varlistentry> | |
293 | ||
798d3a52 ZJS |
294 | <varlistentry> |
295 | <term> | |
296 | <option>driver</option> | |
297 | </term> | |
298 | <listitem> | |
299 | <para>for internally generated messages | |
5199cbe4 | 300 | </para> |
798d3a52 ZJS |
301 | </listitem> |
302 | </varlistentry> | |
303 | ||
304 | <varlistentry> | |
305 | <term> | |
306 | <option>syslog</option> | |
307 | </term> | |
308 | <listitem> | |
309 | <para>for those received via the local syslog socket | |
310 | with the syslog protocol | |
53057ef9 | 311 | </para> |
798d3a52 ZJS |
312 | </listitem> |
313 | </varlistentry> | |
314 | ||
315 | <varlistentry> | |
316 | <term> | |
317 | <option>journal</option> | |
318 | </term> | |
319 | <listitem> | |
320 | <para>for those received via the native journal | |
321 | protocol | |
322 | </para> | |
323 | </listitem> | |
324 | </varlistentry> | |
325 | ||
326 | <varlistentry> | |
327 | <term> | |
328 | <option>stdout</option> | |
329 | </term> | |
330 | <listitem> | |
331 | <para>for those read from a service's standard output | |
332 | or error output | |
333 | </para> | |
334 | </listitem> | |
335 | </varlistentry> | |
336 | ||
337 | <varlistentry> | |
338 | <term> | |
339 | <option>kernel</option> | |
340 | </term> | |
341 | <listitem> | |
342 | <para>for those read from the kernel | |
343 | </para> | |
344 | </listitem> | |
345 | </varlistentry> | |
346 | </variablelist> | |
347 | </listitem> | |
348 | </varlistentry> | |
ec20fe5f LP |
349 | <varlistentry> |
350 | <term><varname>_STREAM_ID=</varname></term> | |
351 | <listitem> | |
ee8f5a58 | 352 | <para>Only applies to <literal>_TRANSPORT=stdout</literal> records: specifies a randomized 128bit ID assigned |
ec20fe5f LP |
353 | to the stream connection when it was first created. This ID is useful to reconstruct individual log streams |
354 | from the log records: all log records carrying the same stream ID originate from the same stream.</para> | |
355 | </listitem> | |
356 | </varlistentry> | |
357 | <varlistentry> | |
358 | <term><varname>_LINE_BREAK=</varname></term> | |
359 | <listitem> | |
a3d9aee1 LP |
360 | <para>Only applies to <literal>_TRANSPORT=stdout</literal> records: indicates that the log message |
361 | in the standard output/error stream was not terminated with a normal newline character | |
362 | (<literal>\n</literal>, i.e. ASCII 10). Specifically, when set this field is one of | |
363 | <option>nul</option> (in case the line was terminated by a NUL byte), <option>line-max</option> (in | |
364 | case the maximum log line length was reached, as configured with <varname>LineMax=</varname> in | |
365 | <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>), | |
366 | <option>eof</option> (if this was the last log record of a stream and the stream ended without a | |
367 | final newline character), or <option>pid-change</option> (if the process which generated the log | |
368 | output changed in the middle of a line). Note that this record is not generated when a normal | |
369 | newline character was used for marking the log line end.</para> | |
ec20fe5f LP |
370 | </listitem> |
371 | </varlistentry> | |
7d8155b3 LP |
372 | <varlistentry> |
373 | <term><varname>_NAMESPACE=</varname></term> | |
374 | ||
375 | <listitem><para>If this file was written by a <command>systemd-journald</command> instance managing a | |
376 | journal namespace that is not the default, this field contains the namespace identifier. See | |
377 | <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
378 | for details about journal namespaces.</para> | |
379 | </listitem> | |
380 | </varlistentry> | |
798d3a52 ZJS |
381 | </variablelist> |
382 | </refsect1> | |
383 | ||
384 | <refsect1> | |
385 | <title>Kernel Journal Fields</title> | |
386 | ||
387 | <para>Kernel fields are fields that are used by messages | |
388 | originating in the kernel and stored in the journal.</para> | |
389 | ||
390 | <variablelist class='journal-directives'> | |
391 | <varlistentry> | |
392 | <term><varname>_KERNEL_DEVICE=</varname></term> | |
393 | <listitem> | |
394 | <para>The kernel device name. If the entry is associated to | |
395 | a block device, the major and minor of the device node, | |
396 | separated by <literal>:</literal> and prefixed by | |
397 | <literal>b</literal>. Similar for character devices but | |
398 | prefixed by <literal>c</literal>. For network devices, this | |
399 | is the interface index prefixed by <literal>n</literal>. For | |
400 | all other devices, this is the subsystem name prefixed by | |
401 | <literal>+</literal>, followed by <literal>:</literal>, | |
402 | followed by the kernel device name.</para> | |
403 | </listitem> | |
404 | </varlistentry> | |
405 | <varlistentry> | |
406 | <term><varname>_KERNEL_SUBSYSTEM=</varname></term> | |
407 | <listitem> | |
408 | <para>The kernel subsystem name.</para> | |
409 | </listitem> | |
410 | </varlistentry> | |
411 | <varlistentry> | |
412 | <term><varname>_UDEV_SYSNAME=</varname></term> | |
413 | <listitem> | |
414 | <para>The kernel device name as it shows up in the device | |
415 | tree below <filename>/sys</filename>.</para> | |
416 | </listitem> | |
417 | </varlistentry> | |
418 | <varlistentry> | |
419 | <term><varname>_UDEV_DEVNODE=</varname></term> | |
420 | <listitem> | |
421 | <para>The device node path of this device in | |
422 | <filename>/dev</filename>.</para> | |
423 | </listitem> | |
424 | </varlistentry> | |
425 | <varlistentry> | |
426 | <term><varname>_UDEV_DEVLINK=</varname></term> | |
427 | <listitem> | |
428 | <para>Additional symlink names pointing to the device node | |
429 | in <filename>/dev</filename>. This field is frequently set | |
430 | more than once per entry.</para> | |
431 | </listitem> | |
432 | </varlistentry> | |
433 | </variablelist> | |
434 | </refsect1> | |
435 | ||
436 | <refsect1> | |
437 | <title>Fields to log on behalf of a different program</title> | |
438 | ||
439 | <para>Fields in this section are used by programs to specify that | |
440 | they are logging on behalf of another program or unit. | |
441 | </para> | |
442 | ||
443 | <para>Fields used by the <command>systemd-coredump</command> | |
444 | coredump kernel helper: | |
445 | </para> | |
446 | ||
447 | <variablelist class='journal-directives'> | |
448 | <varlistentry> | |
449 | <term><varname>COREDUMP_UNIT=</varname></term> | |
450 | <term><varname>COREDUMP_USER_UNIT=</varname></term> | |
451 | <listitem> | |
452 | <para>Used to annotate messages containing coredumps from | |
453 | system and session units. See | |
454 | <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>. | |
455 | </para> | |
456 | </listitem> | |
457 | </varlistentry> | |
458 | </variablelist> | |
459 | ||
ff9b60f3 | 460 | <para>Privileged programs (currently UID 0) may attach |
798d3a52 ZJS |
461 | <varname>OBJECT_PID=</varname> to a message. This will instruct |
462 | <command>systemd-journald</command> to attach additional fields on | |
463 | behalf of the caller:</para> | |
464 | ||
465 | <variablelist class='journal-directives'> | |
466 | <varlistentry> | |
467 | <term><varname>OBJECT_PID=<replaceable>PID</replaceable></varname></term> | |
468 | <listitem> | |
469 | <para>PID of the program that this message pertains to. | |
470 | </para> | |
471 | </listitem> | |
472 | </varlistentry> | |
473 | ||
474 | <varlistentry> | |
475 | <term><varname>OBJECT_UID=</varname></term> | |
476 | <term><varname>OBJECT_GID=</varname></term> | |
477 | <term><varname>OBJECT_COMM=</varname></term> | |
478 | <term><varname>OBJECT_EXE=</varname></term> | |
479 | <term><varname>OBJECT_CMDLINE=</varname></term> | |
480 | <term><varname>OBJECT_AUDIT_SESSION=</varname></term> | |
481 | <term><varname>OBJECT_AUDIT_LOGINUID=</varname></term> | |
482 | <term><varname>OBJECT_SYSTEMD_CGROUP=</varname></term> | |
483 | <term><varname>OBJECT_SYSTEMD_SESSION=</varname></term> | |
484 | <term><varname>OBJECT_SYSTEMD_OWNER_UID=</varname></term> | |
485 | <term><varname>OBJECT_SYSTEMD_UNIT=</varname></term> | |
486 | <term><varname>OBJECT_SYSTEMD_USER_UNIT=</varname></term> | |
487 | <listitem> | |
488 | <para>These are additional fields added automatically by | |
489 | <command>systemd-journald</command>. Their meaning is the | |
490 | same as | |
491 | <varname>_UID=</varname>, | |
492 | <varname>_GID=</varname>, | |
493 | <varname>_COMM=</varname>, | |
494 | <varname>_EXE=</varname>, | |
495 | <varname>_CMDLINE=</varname>, | |
496 | <varname>_AUDIT_SESSION=</varname>, | |
497 | <varname>_AUDIT_LOGINUID=</varname>, | |
498 | <varname>_SYSTEMD_CGROUP=</varname>, | |
499 | <varname>_SYSTEMD_SESSION=</varname>, | |
500 | <varname>_SYSTEMD_UNIT=</varname>, | |
501 | <varname>_SYSTEMD_USER_UNIT=</varname>, and | |
502 | <varname>_SYSTEMD_OWNER_UID=</varname> | |
503 | as described above, except that the process identified by | |
504 | <replaceable>PID</replaceable> is described, instead of the | |
505 | process which logged the message.</para> | |
506 | </listitem> | |
507 | </varlistentry> | |
508 | </variablelist> | |
509 | ||
798d3a52 ZJS |
510 | </refsect1> |
511 | ||
512 | <refsect1> | |
513 | <title>Address Fields</title> | |
514 | ||
515 | <para>During serialization into external formats, such as the | |
516 | <ulink | |
28a0ad81 | 517 | url="https://www.freedesktop.org/wiki/Software/systemd/export">Journal |
798d3a52 | 518 | Export Format</ulink> or the <ulink |
28a0ad81 | 519 | url="https://www.freedesktop.org/wiki/Software/systemd/json">Journal |
798d3a52 ZJS |
520 | JSON Format</ulink>, the addresses of journal entries are |
521 | serialized into fields prefixed with double underscores. Note that | |
522 | these are not proper fields when stored in the journal but for | |
523 | addressing metadata of entries. They cannot be written as part of | |
524 | structured log entries via calls such as | |
525 | <citerefentry><refentrytitle>sd_journal_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
526 | They may also not be used as matches for | |
e9dd6984 ZJS |
527 | <citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>. |
528 | </para> | |
798d3a52 ZJS |
529 | |
530 | <variablelist class='journal-directives'> | |
531 | <varlistentry> | |
532 | <term><varname>__CURSOR=</varname></term> | |
533 | <listitem> | |
534 | <para>The cursor for the entry. A cursor is an opaque text | |
535 | string that uniquely describes the position of an entry in | |
536 | the journal and is portable across machines, platforms and | |
537 | journal files. | |
538 | </para> | |
539 | </listitem> | |
540 | </varlistentry> | |
541 | ||
542 | <varlistentry> | |
543 | <term><varname>__REALTIME_TIMESTAMP=</varname></term> | |
544 | <listitem> | |
545 | <para>The wallclock time | |
546 | (<constant>CLOCK_REALTIME</constant>) at the point in time | |
547 | the entry was received by the journal, in microseconds since | |
548 | the epoch UTC, formatted as a decimal string. This has | |
549 | different properties from | |
550 | <literal>_SOURCE_REALTIME_TIMESTAMP=</literal>, as it is | |
551 | usually a bit later but more likely to be monotonic. | |
552 | </para> | |
553 | </listitem> | |
554 | </varlistentry> | |
555 | ||
556 | <varlistentry> | |
557 | <term><varname>__MONOTONIC_TIMESTAMP=</varname></term> | |
558 | <listitem> | |
559 | <para>The monotonic time | |
560 | (<constant>CLOCK_MONOTONIC</constant>) at the point in time | |
561 | the entry was received by the journal in microseconds, | |
562 | formatted as a decimal string. To be useful as an address | |
563 | for the entry, this should be combined with the boot ID in | |
564 | <literal>_BOOT_ID=</literal>. | |
565 | </para> | |
566 | </listitem> | |
567 | </varlistentry> | |
568 | </variablelist> | |
569 | </refsect1> | |
570 | ||
571 | <refsect1> | |
572 | <title>See Also</title> | |
573 | <para> | |
574 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
5a5bd9f7 | 575 | <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
798d3a52 ZJS |
576 | <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
577 | <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
578 | <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
579 | <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
580 | <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
581 | </para> | |
582 | </refsect1> | |
ffa16db0 LP |
583 | |
584 | </refentry> |