NAME | DESCRIPTION | USER JOURNAL FIELDS | TRUSTED JOURNAL FIELDS | KERNEL JOURNAL FIELDS | FIELDS TO LOG ON BEHALF OF A DIFFERENT PROGRAM | ADDRESS FIELDS | SEE ALSO | NOTES | COLOPHON

SYSTEMD.JOURNAL-FIELDS(7)  systemd.journal-fields  SYSTEMD.JOURNAL-FIELDS(7)

NAME         top

       systemd.journal-fields - Special journal fields

DESCRIPTION         top

       Entries in the journal resemble an environment block in their syntax
       but with fields that can include binary data. Primarily, fields are
       formatted UTF-8 text strings, and binary formatting is used only
       where formatting as UTF-8 text strings makes little sense. New fields
       may freely be defined by applications, but a few fields have special
       meaning. All fields with special meanings are optional. In some
       cases, fields may appear more than once per entry.

USER JOURNAL FIELDS         top

       User fields are fields that are directly passed from clients and
       stored in the journal.

       MESSAGE=
           The human-readable message string for this entry. This is
           supposed to be the primary text shown to the user. It is usually
           not translated (but might be in some cases), and is not supposed
           to be parsed for metadata.

       MESSAGE_ID=
           A 128-bit message identifier ID for recognizing certain message
           types, if this is desirable. This should contain a 128-bit ID
           formatted as a lower-case hexadecimal string, without any
           separating dashes or suchlike. This is recommended to be a
           UUID-compatible ID, but this is not enforced, and formatted
           differently. Developers can generate a new ID for this purpose
           with journalctl --new-id.

       PRIORITY=
           A priority value between 0 ("emerg") and 7 ("debug") formatted as
           a decimal string. This field is compatible with syslog's priority
           concept.

       CODE_FILE=, CODE_LINE=, CODE_FUNC=
           The code location generating this message, if known. Contains the
           source filename, the line number and the function name.

       ERRNO=
           The low-level Unix error number causing this entry, if any.
           Contains the numeric value of errno(3) formatted as a decimal
           string.

       SYSLOG_FACILITY=, SYSLOG_IDENTIFIER=, SYSLOG_PID=
           Syslog compatibility fields containing the facility (formatted as
           decimal string), the identifier string (i.e. "tag"), and the
           client PID. (Note that the tag is usually derived from glibc's
           program_invocation_short_name variable, see
           program_invocation_short_name(3).)

TRUSTED JOURNAL FIELDS         top

       Fields prefixed with an underscore are trusted fields, i.e. fields
       that are implicitly added by the journal and cannot be altered by
       client code.

       _PID=, _UID=, _GID=
           The process, user, and group ID of the process the journal entry
           originates from formatted as a decimal string.

       _COMM=, _EXE=, _CMDLINE=
           The name, the executable path, and the command line of the
           process the journal entry originates from.

       _CAP_EFFECTIVE=
           The effective capabilities(7) of the process the journal entry
           originates from.

       _AUDIT_SESSION=, _AUDIT_LOGINUID=
           The session and login UID of the process the journal entry
           originates from, as maintained by the kernel audit subsystem.

       _SYSTEMD_CGROUP=, _SYSTEMD_SESSION=, _SYSTEMD_UNIT=,
       _SYSTEMD_USER_UNIT=, _SYSTEMD_OWNER_UID=, _SYSTEMD_SLICE=
           The control group path in the systemd hierarchy, the systemd
           session ID (if any), the systemd unit name (if any), the systemd
           user session unit name (if any), the owner UID of the systemd
           session (if any) and the systemd slice unit of the process the
           journal entry originates from.

       _SELINUX_CONTEXT=
           The SELinux security context (label) of the process the journal
           entry originates from.

       _SOURCE_REALTIME_TIMESTAMP=
           The earliest trusted timestamp of the message, if any is known
           that is different from the reception time of the journal. This is
           the time in microseconds since the epoch UTC, formatted as a
           decimal string.

       _BOOT_ID=
           The kernel boot ID for the boot the message was generated in,
           formatted as a 128-bit hexadecimal string.

       _MACHINE_ID=
           The machine ID of the originating host, as available in
           machine-id(5).

       _HOSTNAME=
           The name of the originating host.

       _TRANSPORT=
           How the entry was received by the journal service. Valid
           transports are:

           audit
               for those read from the kernel audit subsystem

           driver
               for internally generated messages

           syslog
               for those received via the local syslog socket with the
               syslog protocol

           journal
               for those received via the native journal protocol

           stdout
               for those read from a service's standard output or error
               output

           kernel
               for those read from the kernel

KERNEL JOURNAL FIELDS         top

       Kernel fields are fields that are used by messages originating in the
       kernel and stored in the journal.

       _KERNEL_DEVICE=
           The kernel device name. If the entry is associated to a block
           device, the major and minor of the device node, separated by ":"
           and prefixed by "b". Similar for character devices but prefixed
           by "c". For network devices, this is the interface index prefixed
           by "n". For all other devices, this is the subsystem name
           prefixed by "+", followed by ":", followed by the kernel device
           name.

       _KERNEL_SUBSYSTEM=
           The kernel subsystem name.

       _UDEV_SYSNAME=
           The kernel device name as it shows up in the device tree below
           /sys.

       _UDEV_DEVNODE=
           The device node path of this device in /dev.

       _UDEV_DEVLINK=
           Additional symlink names pointing to the device node in /dev.
           This field is frequently set more than once per entry.

FIELDS TO LOG ON BEHALF OF A DIFFERENT PROGRAM         top

       Fields in this section are used by programs to specify that they are
       logging on behalf of another program or unit.

       Fields used by the systemd-coredump coredump kernel helper:

       COREDUMP_UNIT=, COREDUMP_USER_UNIT=
           Used to annotate messages containing coredumps from system and
           session units. See coredumpctl(1).

       Privileged programs (currently UID 0) may attach OBJECT_PID= to a
       message. This will instruct systemd-journald to attach additional
       fields on behalf of the caller:

       OBJECT_PID=PID
           PID of the program that this message pertains to.

       OBJECT_UID=, OBJECT_GID=, OBJECT_COMM=, OBJECT_EXE=, OBJECT_CMDLINE=,
       OBJECT_AUDIT_SESSION=, OBJECT_AUDIT_LOGINUID=,
       OBJECT_SYSTEMD_CGROUP=, OBJECT_SYSTEMD_SESSION=,
       OBJECT_SYSTEMD_OWNER_UID=, OBJECT_SYSTEMD_UNIT=,
       OBJECT_SYSTEMD_USER_UNIT=
           These are additional fields added automatically by
           systemd-journald. Their meaning is the same as _UID=, _GID=,
           _COMM=, _EXE=, _CMDLINE=, _AUDIT_SESSION=, _AUDIT_LOGINUID=,
           _SYSTEMD_CGROUP=, _SYSTEMD_SESSION=, _SYSTEMD_UNIT=,
           _SYSTEMD_USER_UNIT=, and _SYSTEMD_OWNER_UID= as described above,
           except that the process identified by PID is described, instead
           of the process which logged the message.

ADDRESS FIELDS         top

       During serialization into external formats, such as the Journal
       Export Format[1] or the Journal JSON Format[2], the addresses of
       journal entries are serialized into fields prefixed with double
       underscores. Note that these are not proper fields when stored in the
       journal but for addressing metadata of entries. They cannot be
       written as part of structured log entries via calls such as
       sd_journal_send(3). They may also not be used as matches for
       sd_journal_add_match(3)

       __CURSOR=
           The cursor for the entry. A cursor is an opaque text string that
           uniquely describes the position of an entry in the journal and is
           portable across machines, platforms and journal files.

       __REALTIME_TIMESTAMP=
           The wallclock time (CLOCK_REALTIME) at the point in time the
           entry was received by the journal, in microseconds since the
           epoch UTC, formatted as a decimal string. This has different
           properties from "_SOURCE_REALTIME_TIMESTAMP=", as it is usually a
           bit later but more likely to be monotonic.

       __MONOTONIC_TIMESTAMP=
           The monotonic time (CLOCK_MONOTONIC) at the point in time the
           entry was received by the journal in microseconds, formatted as a
           decimal string. To be useful as an address for the entry, this
           should be combined with the boot ID in "_BOOT_ID=".

SEE ALSO         top

       systemd(1), journalctl(1), journald.conf(5), sd-journal(3),
       coredumpctl(1), systemd.directives(7)

NOTES         top

        1. Journal Export Format
           http://www.freedesktop.org/wiki/Software/systemd/export

        2. Journal JSON Format
           http://www.freedesktop.org/wiki/Software/systemd/json

COLOPHON         top

       This page is part of the systemd (systemd system and service manager)
       project.  Information about the project can be found at 
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have a bug
       report for this manual page, see 
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.  This
       page was obtained from the project's upstream Git repository 
       ⟨https://github.com/systemd/systemd.git⟩ on 2016-10-04.  If you dis‐
       cover any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page, or
       you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail
       to man-pages@man7.org

systemd 231                                        SYSTEMD.JOURNAL-FIELDS(7)