man/systemd.journal-fields.xml

   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
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   6   This file is part of systemd.
   7
   8   Copyright 2010 Lennart Poettering
   9
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  14
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  18   Lesser General Public License for more details.
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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, 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>
  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>_AUDIT_SESSION=</varname></term>
 201                                 <term><varname>_AUDIT_LOGINUID=</varname></term>
 202                                 <listitem>
 203                                         <para>The session and login
 204                                         UID of the process the journal
 205                                         entry originates from, as
 206                                         maintained by the kernel audit
 207                                         subsystem.</para>
 208                                 </listitem>
 209                         </varlistentry>
 210
 211                         <varlistentry>
 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>
 217
 218                                 <listitem>
 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>
 228                                 </listitem>
 229                         </varlistentry>
 230
 231                         <varlistentry>
 232                                 <term><varname>_SELINUX_CONTEXT=</varname></term>
 233                                 <listitem>
 234                                         <para>The SELinux security
 235                                         context of the process the
 236                                         journal entry originates
 237                                         from.</para>
 238                                 </listitem>
 239                         </varlistentry>
 240
 241                         <varlistentry>
 242                                 <term><varname>_SOURCE_REALTIME_TIMESTAMP=</varname></term>
 243                                 <listitem>
 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                                         microseconds since the epoch UTC,
 250                                         formatted as a decimal
 251                                         string.</para>
 252                                 </listitem>
 253                         </varlistentry>
 254
 255                         <varlistentry>
 256                                 <term><varname>_BOOT_ID=</varname></term>
 257                                 <listitem>
 258                                         <para>The kernel boot ID for
 259                                         the boot the message was
 260                                         generated in, formatted as
 261                                         a 128-bit hexadecimal
 262                                         string.</para>
 263                                 </listitem>
 264                         </varlistentry>
 265
 266                         <varlistentry>
 267                                 <term><varname>_MACHINE_ID=</varname></term>
 268                                 <listitem>
 269                                         <para>The machine ID of the
 270                                         originating host, as available
 271                                         in
 272                                         <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 273                                 </listitem>
 274                         </varlistentry>
 275
 276                         <varlistentry>
 277                                 <term><varname>_HOSTNAME=</varname></term>
 278                                 <listitem>
 279                                         <para>The name of the
 280                                         originating host.</para>
 281                                 </listitem>
 282                         </varlistentry>
 283
 284                         <varlistentry>
 285                                 <term><varname>_TRANSPORT=</varname></term>
 286                                 <listitem>
 287                                         <para>How the entry was
 288                                         received by the journal
 289                                         service. Valid transports are:
 290                                         </para>
 291                                         <variablelist>
 292                                                 <varlistentry>
 293                                                         <term>
 294                                                                 <option>driver</option>
 295                                                         </term>
 296                                                         <listitem>
 297                                                                 <para>for
 298                                                                 internally
 299                                                                 generated
 300                                                                 messages
 301                                                                 </para>
 302                                                         </listitem>
 303                                                 </varlistentry>
 304
 305                                                 <varlistentry>
 306                                                         <term>
 307                                                                 <option>syslog</option>
 308                                                         </term>
 309                                                         <listitem>
 310                                                                 <para>for those
 311                                                                 received via the
 312                                                                 local syslog
 313                                                                 socket with the
 314                                                                 syslog protocol
 315                                                                 </para>
 316                                                         </listitem>
 317                                                 </varlistentry>
 318
 319                                                 <varlistentry>
 320                                                         <term>
 321                                                                 <option>journal</option>
 322                                                         </term>
 323                                                         <listitem>
 324                                                                 <para>for those
 325                                                                 received via the
 326                                                                 native journal
 327                                                                 protocol
 328                                                                 </para>
 329                                                         </listitem>
 330                                                 </varlistentry>
 331
 332                                                 <varlistentry>
 333                                                         <term>
 334                                                                 <option>stdout</option>
 335                                                         </term>
 336                                                         <listitem>
 337                                                                 <para>for those
 338                                                                 read from a
 339                                                                 service's
 340                                                                 standard output
 341                                                                 or error output
 342                                                                 </para>
 343                                                         </listitem>
 344                                                 </varlistentry>
 345
 346                                                 <varlistentry>
 347                                                         <term>
 348                                                                 <option>kernel</option>
 349                                                         </term>
 350                                                         <listitem>
 351                                                                 <para>for those
 352                                                                 read from the
 353                                                                 kernel
 354                                                                 </para>
 355                                                         </listitem>
 356                                                 </varlistentry>
 357                                         </variablelist>
 358                                 </listitem>
 359                         </varlistentry>
 360                 </variablelist>
 361         </refsect1>
 362
 363         <refsect1>
 364                 <title>Kernel Journal Fields</title>
 365
 366                 <para>Kernel fields are fields that are used by
 367                 messages originating in the kernel and stored in the
 368                 journal.</para>
 369
 370                 <variablelist class='journal-directives'>
 371                         <varlistentry>
 372                                 <term><varname>_KERNEL_DEVICE=</varname></term>
 373                                 <listitem>
 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
 387                                         device name.</para>
 388                                 </listitem>
 389                         </varlistentry>
 390                         <varlistentry>
 391                                 <term><varname>_KERNEL_SUBSYSTEM=</varname></term>
 392                                 <listitem>
 393                                         <para>The kernel subsystem name.</para>
 394                                 </listitem>
 395                         </varlistentry>
 396                         <varlistentry>
 397                                 <term><varname>_UDEV_SYSNAME=</varname></term>
 398                                 <listitem>
 399                                         <para>The kernel device name
 400                                         as it shows up in the device
 401                                         tree below
 402                                         <filename>/sys</filename>.</para>
 403                                 </listitem>
 404                         </varlistentry>
 405                         <varlistentry>
 406                                 <term><varname>_UDEV_DEVNODE=</varname></term>
 407                                 <listitem>
 408                                         <para>The device node path of
 409                                         this device in
 410                                         <filename>/dev</filename>.</para>
 411                                 </listitem>
 412                         </varlistentry>
 413                         <varlistentry>
 414                                 <term><varname>_UDEV_DEVLINK=</varname></term>
 415                                 <listitem>
 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>
 421                                 </listitem>
 422                         </varlistentry>
 423                 </variablelist>
 424         </refsect1>
 425
 426         <refsect1>
 427                 <title>Fields to log on behalf of a different program</title>
 428
 429                 <para>Fields in this section are used by programs
 430                 to specify that they are logging on behalf of another
 431                 program or unit.
 432                 </para>
 433
 434                 <para>Fields used by the <command>systemd-coredump</command>
 435                 coredump kernel helper:
 436                 </para>
 437
 438                 <variablelist class='journal-directives'>
 439                         <varlistentry>
 440                                 <term><varname>COREDUMP_UNIT=</varname></term>
 441                                 <term><varname>COREDUMP_USER_UNIT=</varname></term>
 442                                 <listitem>
 443                                         <para>Used to annotate
 444                                         messages containing coredumps from
 445                                         system and session units.
 446                                         See
 447                                         <citerefentry><refentrytitle>systemd-coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
 448                                         </para>
 449                                 </listitem>
 450                         </varlistentry>
 451                 </variablelist>
 452
 453                 <para>Priviledged programs (currently UID 0) may
 454                 attach <varname>OBJECT_PID=</varname> to a
 455                 message. This will instruct
 456                 <command>systemd-journald</command> to attach
 457                 additional fields on behalf of the caller:</para>
 458
 459                 <variablelist class='journal-directives'>
 460                         <varlistentry>
 461                                 <term><varname>OBJECT_PID=<replaceable>PID</replaceable></varname></term>
 462                                 <listitem>
 463                                         <para>PID of the program that this
 464                                         message pertains to.
 465                                         </para>
 466                                 </listitem>
 467                         </varlistentry>
 468
 469                         <varlistentry>
 470                                 <term><varname>OBJECT_UID=</varname></term>
 471                                 <term><varname>OBJECT_GID=</varname></term>
 472                                 <term><varname>OBJECT_COMM=</varname></term>
 473                                 <term><varname>OBJECT_EXE=</varname></term>
 474                                 <term><varname>OBJECT_CMDLINE=</varname></term>
 475                                 <term><varname>OBJECT_AUDIT_SESSION=</varname></term>
 476                                 <term><varname>OBJECT_AUDIT_LOGINUID=</varname></term>
 477                                 <term><varname>OBJECT_SYSTEMD_CGROUP=</varname></term>
 478                                 <term><varname>OBJECT_SYSTEMD_SESSION=</varname></term>
 479                                 <term><varname>OBJECT_SYSTEMD_OWNER_UID=</varname></term>
 480                                 <term><varname>OBJECT_SYSTEMD_UNIT=</varname></term>
 481                                 <term><varname>OBJECT_SYSTEMD_USER_UNIT=</varname></term>
 482                                 <listitem>
 483                                         <para>These are additional fields added automatically
 484                                         by <command>systemd-journald</command>.
 485                                         Their meaning is the same as
 486                                         <varname>_UID=</varname>,
 487                                         <varname>_GID=</varname>,
 488                                         <varname>_COMM=</varname>,
 489                                         <varname>_EXE=</varname>,
 490                                         <varname>_CMDLINE=</varname>,
 491                                         <varname>_AUDIT_SESSION=</varname>,
 492                                         <varname>_AUDIT_LOGINUID=</varname>,
 493                                         <varname>_SYSTEMD_CGROUP=</varname>,
 494                                         <varname>_SYSTEMD_SESSION=</varname>,
 495                                         <varname>_SYSTEMD_UNIT=</varname>,
 496                                         <varname>_SYSTEMD_USER_UNIT=</varname>, and
 497                                         <varname>_SYSTEMD_OWNER_UID=</varname>
 498                                         as described above, except that the
 499                                         process identified by <replaceable>PID</replaceable>
 500                                         is described, instead of the process
 501                                         which logged the message.</para>
 502                                 </listitem>
 503                         </varlistentry>
 504                 </variablelist>
 505
 506
 507         </refsect1>
 508
 509         <refsect1>
 510                 <title>Address Fields</title>
 511
 512                 <para>During serialization into external formats, such
 513                 as the <ulink
 514                 url="http://www.freedesktop.org/wiki/Software/systemd/export">Journal
 515                 Export Format</ulink> or the <ulink
 516                 url="http://www.freedesktop.org/wiki/Software/systemd/json">Journal
 517                 JSON Format</ulink>, the addresses of journal entries
 518                 are serialized into fields prefixed with double
 519                 underscores. Note that these aren't proper fields when
 520                 stored in the journal but for addressing meta data of
 521                 entries. They cannot be written as part of structured
 522                 log entries via calls such as
 523                 <citerefentry><refentrytitle>sd_journal_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>. They
 524                 may also not be used as matches for
 525                 <citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry></para>
 526
 527                 <variablelist class='journal-directives'>
 528                         <varlistentry>
 529                                 <term><varname>__CURSOR=</varname></term>
 530                                 <listitem>
 531                                         <para>The cursor for the
 532                                         entry. A cursor is an opaque
 533                                         text string that uniquely
 534                                         describes the position of an
 535                                         entry in the journal and is
 536                                         portable across machines,
 537                                         platforms and 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>)
 547                                         at the point in time the entry
 548                                         was received by the journal,
 549                                         in microseconds since the epoch
 550                                         UTC, formatted as a decimal
 551                                         string. This has different
 552                                         properties from
 553                                         <literal>_SOURCE_REALTIME_TIMESTAMP=</literal>,
 554                                         as it is usually a bit later
 555                                         but more likely to be monotonic.
 556                                         </para>
 557                                 </listitem>
 558                         </varlistentry>
 559
 560                         <varlistentry>
 561                                 <term><varname>__MONOTONIC_TIMESTAMP=</varname></term>
 562                                 <listitem>
 563                                         <para>The monotonic time
 564                                         (<constant>CLOCK_MONOTONIC</constant>)
 565                                         at the point in time the entry
 566                                         was received by the journal in
 567                                         microseconds, formatted as a decimal
 568                                         string. To be useful as an
 569                                         address for the entry, this
 570                                         should be combined with with the
 571                                         boot ID in <literal>_BOOT_ID=</literal>.
 572                                         </para>
 573                                 </listitem>
 574                         </varlistentry>
 575                 </variablelist>
 576         </refsect1>
 577
 578         <refsect1>
 579                   <title>See Also</title>
 580                   <para>
 581                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 582                           <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 583                           <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 584                           <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 585                           <citerefentry><refentrytitle>systemd-coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 586                           <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 587                   </para>
 588         </refsect1>
 589
 590 </refentry>