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">
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   6   This file is part of systemd.
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   8   Copyright 2010 Lennart Poettering
   9
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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 128bit message
  91                                         identifier ID for recognizing
  92                                         certain message types, if this
  93                                         is desirable. This should
  94                                         contain a 128bit id formatted
  95                                         as lower-case hexadecimal
  96                                         string, without any separating
  97                                         dashes or suchlike. This is
  98                                         recommended to be a UUID
  99                                         compatible ID, but this is not
 100                                         enforced, and formatted
 101                                         differently. Developers can
 102                                         generate a new ID for this
 103                                         purpose with
 104                                         <command>journalctl
 105                                         --new-id</command>.</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 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                                         file name, 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 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 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                                         usec since the epoch UTC
 250                                         formatted as 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                                         128bit 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. One of
 290                                         <literal>driver</literal>,
 291                                         <literal>syslog</literal>,
 292                                         <literal>journal</literal>,
 293                                         <literal>stdout</literal>,
 294                                         <literal>kernel</literal> for
 295                                         internally generated messages,
 296                                         for those received via the
 297                                         local syslog socket with the
 298                                         syslog protocol, for those
 299                                         received via the native
 300                                         journal protocol, for the
 301                                         those read from a services'
 302                                         standard output or error
 303                                         output, or for those read
 304                                         from the kernel, respectively.
 305                                         </para>
 306                                 </listitem>
 307                         </varlistentry>
 308                 </variablelist>
 309         </refsect1>
 310
 311         <refsect1>
 312                 <title>Kernel Journal Fields</title>
 313
 314                 <para>Kernel fields are fields that are used by
 315                 messages originating in the kernel and stored in the
 316                 journal.</para>
 317
 318                 <variablelist>
 319                         <varlistentry>
 320                                 <term>_KERNEL_DEVICE=</term>
 321                                 <listitem>
 322                                         <para>The kernel device
 323                                         name. If the entry is
 324                                         associated to a block device,
 325                                         the major and minor of the
 326                                         device node, separated by ':'
 327                                         and prefixed by 'b'. Similar
 328                                         for character devices, but
 329                                         prefixed by 'c'. For network
 330                                         devices the interface index,
 331                                         prefixed by 'n'. For all other
 332                                         devices '+' followed by the
 333                                         subsystem name, followed by
 334                                         ':', followed by the kernel
 335                                         device name.</para>
 336                                 </listitem>
 337                         </varlistentry>
 338                         <varlistentry>
 339                                 <term>_KERNEL_SUBSYSTEM=</term>
 340                                 <listitem>
 341                                         <para>The kernel subsystem name.</para>
 342                                 </listitem>
 343                         </varlistentry>
 344                         <varlistentry>
 345                                 <term>_UDEV_SYSNAME=</term>
 346                                 <listitem>
 347                                         <para>The kernel device name
 348                                         as it shows up in the device
 349                                         tree below
 350                                         <filename>/sys</filename>.</para>
 351                                 </listitem>
 352                         </varlistentry>
 353                         <varlistentry>
 354                                 <term>_UDEV_DEVNODE=</term>
 355                                 <listitem>
 356                                         <para>The device node path of
 357                                         this device in
 358                                         <filename>/dev</filename>.</para>
 359                                 </listitem>
 360                         </varlistentry>
 361                         <varlistentry>
 362                                 <term>_UDEV_DEVLINK=</term>
 363                                 <listitem>
 364                                         <para>Additional symlink names
 365                                         pointing to the device node in
 366                                         <filename>/dev</filename>. This
 367                                         field is frequently set more
 368                                         than once per entry.</para>
 369                                 </listitem>
 370                         </varlistentry>
 371                 </variablelist>
 372         </refsect1>
 373
 374         <refsect1>
 375                 <title>Address Fields</title>
 376
 377                 <para>During serialization into external formats, such
 378                 as the <ulink
 379                 url="http://www.freedesktop.org/wiki/Software/systemd/export">Journal
 380                 Export Format</ulink> or the <ulink
 381                 url="http://www.freedesktop.org/wiki/Software/systemd/json">Journal
 382                 JSON Format</ulink>, the addresses of journal entries
 383                 are serialized into fields prefixed with double
 384                 underscores. Note that these aren't proper fields when
 385                 stored in the journal, but addressing meta data of
 386                 entries. They cannot be written as part of structured
 387                 log entries via calls such as
 388                 <citerefentry><refentrytitle>sd_journal_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>. They
 389                 may also not be used as matches for
 390                 <citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry></para>
 391
 392                 <variablelist class='journal-directives'>
 393                         <varlistentry>
 394                                 <term><varname>__CURSOR=</varname></term>
 395                                 <listitem>
 396                                         <para>The cursor for the
 397                                         entry. A cursor is an opaque
 398                                         text string that uniquely
 399                                         describes the position of an
 400                                         entry in the journal and is
 401                                         portable across machines,
 402                                         platforms and journal
 403                                         files.</para>
 404                                 </listitem>
 405                         </varlistentry>
 406
 407                         <varlistentry>
 408                                 <term><varname>__REALTIME_TIMESTAMP=</varname></term>
 409                                 <listitem>
 410                                         <para>The wallclock time
 411                                         (CLOCK_REALTIME) at the point
 412                                         in time the entry was received
 413                                         by the journal, in usec since
 414                                         the epoch UTC formatted as
 415                                         decimal string. This has
 416                                         different properties from
 417                                         <literal>_SOURCE_REALTIME_TIMESTAMP=</literal>
 418                                         as it is usually a bit later
 419                                         but more likely to be
 420                                         monotonic.</para>
 421                                 </listitem>
 422                         </varlistentry>
 423
 424                         <varlistentry>
 425                                 <term><varname>__MONOTONIC_TIMESTAMP=</varname></term>
 426                                 <listitem>
 427                                         <para>The monotonic time
 428                                         (CLOCK_MONOTONIC) at the point
 429                                         in time the entry was received
 430                                         by the journal in usec
 431                                         formatted as decimal
 432                                         string. To be useful as an
 433                                         address for the entry this
 434                                         should be combined with with
 435                                         boot ID in
 436                                         <literal>_BOOT_ID=</literal>.</para>
 437                                 </listitem>
 438                         </varlistentry>
 439                 </variablelist>
 440         </refsect1>
 441
 442         <refsect1>
 443                   <title>See Also</title>
 444                   <para>
 445                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 446                           <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 447                           <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 448                           <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 449                           <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 450                   </para>
 451         </refsect1>
 452
 453 </refentry>