man/systemd.journal-fields.xml

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  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 but 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>
  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
  71                 <variablelist class='journal-directives'>
  72                         <varlistentry>
  73                                 <term><varname>MESSAGE=</varname></term>
  74                                 <listitem>
  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
  83                                         data.</para>
  84                                 </listitem>
  85                         </varlistentry>
  86
  87                         <varlistentry>
  88                                 <term><varname>MESSAGE_ID=</varname></term>
  89                                 <listitem>
  90                                         <para>A 128-bit message
  91                                         identifier ID for recognizing
  92                                         certain message types, if this
  93                                         is desirable. This should
  94                                         contain a 128-bit ID formatted
  95                                         as a lower-case hexadecimal
  96                                         string, without any separating
  97                                         dashes or suchlike. This is
  98                                         recommended to be a
  99                                         UUID-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>.
 105                                         </para>
 106                                 </listitem>
 107                         </varlistentry>
 108
 109                         <varlistentry>
 110                                 <term><varname>PRIORITY=</varname></term>
 111                                 <listitem>
 112                                         <para>A priority value between
 113                                         0 (<literal>emerg</literal>)
 114                                         and 7
 115                                         (<literal>debug</literal>)
 116                                         formatted as a decimal
 117                                         string. This field is
 118                                         compatible with syslog's
 119                                         priority concept.</para>
 120                                 </listitem>
 121                         </varlistentry>
 122
 123                         <varlistentry>
 124                                 <term><varname>CODE_FILE=</varname></term>
 125                                 <term><varname>CODE_LINE=</varname></term>
 126                                 <term><varname>CODE_FUNC=</varname></term>
 127                                 <listitem>
 128                                         <para>The code location
 129                                         generating this message, if
 130                                         known. Contains the source
 131                                         filename, the line number and
 132                                         the function name.</para>
 133                                 </listitem>
 134                         </varlistentry>
 135
 136                         <varlistentry>
 137                                 <term><varname>ERRNO=</varname></term>
 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>
 144                                         formatted as a decimal
 145                                         string.</para>
 146                                 </listitem>
 147                         </varlistentry>
 148
 149                         <varlistentry>
 150                                 <term><varname>SYSLOG_FACILITY=</varname></term>
 151                                 <term><varname>SYSLOG_IDENTIFIER=</varname></term>
 152                                 <term><varname>SYSLOG_PID=</varname></term>
 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
 173                 <variablelist class='journal-directives'>
 174                         <varlistentry>
 175                                 <term><varname>_PID=</varname></term>
 176                                 <term><varname>_UID=</varname></term>
 177                                 <term><varname>_GID=</varname></term>
 178                                 <listitem>
 179                                         <para>The process, user, and
 180                                         group ID of the process the
 181                                         journal entry originates from
 182                                         formatted as a decimal
 183                                         string.</para>
 184                                 </listitem>
 185                         </varlistentry>
 186
 187                         <varlistentry>
 188                                 <term><varname>_COMM=</varname></term>
 189                                 <term><varname>_EXE=</varname></term>
 190                                 <term><varname>_CMDLINE=</varname></term>
 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
 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
 208                         <varlistentry>
 209                                 <term><varname>_AUDIT_SESSION=</varname></term>
 210                                 <term><varname>_AUDIT_LOGINUID=</varname></term>
 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>
 221                                 <term><varname>_SYSTEMD_CGROUP=</varname></term>
 222                                 <term><varname>_SYSTEMD_SESSION=</varname></term>
 223                                 <term><varname>_SYSTEMD_UNIT=</varname></term>
 224                                 <term><varname>_SYSTEMD_USER_UNIT=</varname></term>
 225                                 <term><varname>_SYSTEMD_OWNER_UID=</varname></term>
 226                                 <term><varname>_SYSTEMD_SLICE=</varname></term>
 227
 228                                 <listitem>
 229                                         <para>The control group path
 230                                         in the systemd hierarchy, the
 231                                         systemd session ID (if any),
 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>
 240                                 </listitem>
 241                         </varlistentry>
 242
 243                         <varlistentry>
 244                                 <term><varname>_SELINUX_CONTEXT=</varname></term>
 245                                 <listitem>
 246                                         <para>The SELinux security
 247                                         context (label) of the process
 248                                         the journal entry originates
 249                                         from.</para>
 250                                 </listitem>
 251                         </varlistentry>
 252
 253                         <varlistentry>
 254                                 <term><varname>_SOURCE_REALTIME_TIMESTAMP=</varname></term>
 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
 260                                         journal. This is the time in
 261                                         microseconds since the epoch UTC,
 262                                         formatted as a decimal
 263                                         string.</para>
 264                                 </listitem>
 265                         </varlistentry>
 266
 267                         <varlistentry>
 268                                 <term><varname>_BOOT_ID=</varname></term>
 269                                 <listitem>
 270                                         <para>The kernel boot ID for
 271                                         the boot the message was
 272                                         generated in, formatted as
 273                                         a 128-bit hexadecimal
 274                                         string.</para>
 275                                 </listitem>
 276                         </varlistentry>
 277
 278                         <varlistentry>
 279                                 <term><varname>_MACHINE_ID=</varname></term>
 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>
 289                                 <term><varname>_HOSTNAME=</varname></term>
 290                                 <listitem>
 291                                         <para>The name of the
 292                                         originating host.</para>
 293                                 </listitem>
 294                         </varlistentry>
 295
 296                         <varlistentry>
 297                                 <term><varname>_TRANSPORT=</varname></term>
 298                                 <listitem>
 299                                         <para>How the entry was
 300                                         received by the journal
 301                                         service. Valid transports are:
 302                                         </para>
 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>
 370                                 </listitem>
 371                         </varlistentry>
 372                 </variablelist>
 373         </refsect1>
 374
 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
 382                 <variablelist class='journal-directives'>
 383                         <varlistentry>
 384                                 <term><varname>_KERNEL_DEVICE=</varname></term>
 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
 390                                         device node, separated by <literal>:</literal>
 391                                         and prefixed by <literal>b</literal>. Similar
 392                                         for character devices but
 393                                         prefixed by <literal>c</literal>. For network
 394                                         devices, this is the interface index
 395                                         prefixed by <literal>n</literal>. For all other
 396                                         devices, this is the subsystem name
 397                                         prefixed by <literal>+</literal>, followed by
 398                                         <literal>:</literal>, followed by the kernel
 399                                         device name.</para>
 400                                 </listitem>
 401                         </varlistentry>
 402                         <varlistentry>
 403                                 <term><varname>_KERNEL_SUBSYSTEM=</varname></term>
 404                                 <listitem>
 405                                         <para>The kernel subsystem name.</para>
 406                                 </listitem>
 407                         </varlistentry>
 408                         <varlistentry>
 409                                 <term><varname>_UDEV_SYSNAME=</varname></term>
 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>
 418                                 <term><varname>_UDEV_DEVNODE=</varname></term>
 419                                 <listitem>
 420                                         <para>The device node path of
 421                                         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
 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>
 435                 </variablelist>
 436         </refsect1>
 437
 438         <refsect1>
 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>
 445
 446                 <para>Fields used by the <command>systemd-coredump</command>
 447                 coredump kernel helper:
 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>
 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
 469                 additional fields on behalf of the caller:</para>
 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>
 495                                         <para>These are additional fields added automatically
 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>
 510                                         as described above, except that the
 511                                         process identified by <replaceable>PID</replaceable>
 512                                         is described, instead of the process
 513                                         which logged the message.</para>
 514                                 </listitem>
 515                         </varlistentry>
 516                 </variablelist>
 517
 518
 519         </refsect1>
 520
 521         <refsect1>
 522                 <title>Address Fields</title>
 523
 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
 531                 underscores. Note that these are not proper fields when
 532                 stored in the journal but for addressing meta data of
 533                 entries. They cannot be written as part of structured
 534                 log entries via calls such as
 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>
 538
 539                 <variablelist class='journal-directives'>
 540                         <varlistentry>
 541                                 <term><varname>__CURSOR=</varname></term>
 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,
 549                                         platforms and journal files.
 550                                         </para>
 551                                 </listitem>
 552                         </varlistentry>
 553
 554                         <varlistentry>
 555                                 <term><varname>__REALTIME_TIMESTAMP=</varname></term>
 556                                 <listitem>
 557                                         <para>The wallclock time
 558                                         (<constant>CLOCK_REALTIME</constant>)
 559                                         at the point in time the entry
 560                                         was received by the journal,
 561                                         in microseconds since the epoch
 562                                         UTC, formatted as a decimal
 563                                         string. This has different
 564                                         properties from
 565                                         <literal>_SOURCE_REALTIME_TIMESTAMP=</literal>,
 566                                         as it is usually a bit later
 567                                         but more likely to be monotonic.
 568                                         </para>
 569                                 </listitem>
 570                         </varlistentry>
 571
 572                         <varlistentry>
 573                                 <term><varname>__MONOTONIC_TIMESTAMP=</varname></term>
 574                                 <listitem>
 575                                         <para>The monotonic time
 576                                         (<constant>CLOCK_MONOTONIC</constant>)
 577                                         at the point in time the entry
 578                                         was received by the journal in
 579                                         microseconds, formatted as a decimal
 580                                         string. To be useful as an
 581                                         address for the entry, this
 582                                         should be combined with with the
 583                                         boot ID in <literal>_BOOT_ID=</literal>.
 584                                         </para>
 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>,
 595                           <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 596                           <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 597                           <citerefentry><refentrytitle>systemd-coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 598                           <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 599                   </para>
 600         </refsect1>
 601
 602 </refentry>