Provided by: systemd_252.5-2ubuntu3_amd64 bug


       journalctl - Query the systemd journal


       journalctl [OPTIONS...] [MATCHES...]


       journalctl may be used to query the contents of the systemd(1) journal as written by

       If called without parameters, it will show the full contents of the journal, starting with
       the oldest entry collected.

       If one or more match arguments are passed, the output is filtered accordingly. A match is
       in the format "FIELD=VALUE", e.g.  "_SYSTEMD_UNIT=httpd.service", referring to the
       components of a structured journal entry. See systemd.journal-fields(7) for a list of
       well-known fields. If multiple matches are specified matching different fields, the log
       entries are filtered by both, i.e. the resulting output will show only entries matching
       all the specified matches of this kind. If two matches apply to the same field, then they
       are automatically matched as alternatives, i.e. the resulting output will show entries
       matching any of the specified matches for the same field. Finally, the character "+" may
       appear as a separate word between other terms on the command line. This causes all matches
       before and after to be combined in a disjunction (i.e. logical OR).

       It is also possible to filter the entries by specifying an absolute file path as an
       argument. The file path may be a file or a symbolic link and the file must exist at the
       time of the query. If a file path refers to an executable binary, an "_EXE=" match for the
       canonicalized binary path is added to the query. If a file path refers to an executable
       script, a "_COMM=" match for the script name is added to the query. If a file path refers
       to a device node, "_KERNEL_DEVICE=" matches for the kernel name of the device and for each
       of its ancestor devices is added to the query. Symbolic links are dereferenced, kernel
       names are synthesized, and parent devices are identified from the environment at the time
       of the query. In general, a device node is the best proxy for an actual device, as log
       entries do not usually contain fields that identify an actual device. For the resulting
       log entries to be correct for the actual device, the relevant parts of the environment at
       the time the entry was logged, in particular the actual device corresponding to the device
       node, must have been the same as those at the time of the query. Because device nodes
       generally change their corresponding devices across reboots, specifying a device node path
       causes the resulting entries to be restricted to those from the current boot.

       Additional constraints may be added using options --boot, --unit=, etc., to further limit
       what entries will be shown (logical AND).

       Output is interleaved from all accessible journal files, whether they are rotated or
       currently being written, and regardless of whether they belong to the system itself or are
       accessible user journals. The --header option can be used to identify which files are
       being shown.

       The set of journal files which will be used can be modified using the --user, --system,
       --directory, and --file options, see below.

       All users are granted access to their private per-user journals. However, by default, only
       root and users who are members of a few special groups are granted access to the system
       journal and the journals of other users. Members of the groups "systemd-journal", "adm",
       and "wheel" can read all journal files. Note that the two latter groups traditionally have
       additional privileges specified by the distribution. Members of the "wheel" group can
       often perform administrative tasks.

       The output is paged through less by default, and long lines are "truncated" to screen
       width. The hidden part can be viewed by using the left-arrow and right-arrow keys. Paging
       can be disabled; see the --no-pager option and the "Environment" section below.

       When outputting to a tty, lines are colored according to priority: lines of level ERROR
       and higher are colored red; lines of level NOTICE and higher are highlighted; lines of
       level DEBUG are colored lighter grey; other lines are displayed normally.


       The following options control where to read journal records from:

       --system, --user
           Show messages from system services and the kernel (with --system). Show messages from
           service of current user (with --user). If neither is specified, show all messages that
           the user can see.

           The --user option affects how --unit arguments are treated. See --unit.

       -M, --machine=
           Show messages from a running, local container. Specify a container name to connect to.

       -m, --merge
           Show entries interleaved from all available journals, including remote ones.

       -D DIR, --directory=DIR
           Takes a directory path as argument. If specified, journalctl will operate on the
           specified journal directory DIR instead of the default runtime and system journal

           Takes a file glob as an argument. If specified, journalctl will operate on the
           specified journal files matching GLOB instead of the default runtime and system
           journal paths. May be specified multiple times, in which case files will be suitably

           Takes a directory path as an argument. If specified, journalctl will operate on
           journal directories and catalog file hierarchy underneath the specified directory
           instead of the root directory (e.g.  --update-catalog will create
           ROOT/var/lib/systemd/catalog/database, and journal files under ROOT/run/journal/ or
           ROOT/var/log/journal/ will be displayed).

           Takes a path to a disk image file or block device node. If specified, journalctl will
           operate on the file system in the indicated disk image. This option is similar to
           --root=, but operates on file systems stored in disk images or block devices, thus
           providing an easy way to extract log data from disk images. The disk image should
           either contain just a file system or a set of file systems within a GPT partition
           table, following the Discoverable Partitions Specification[1]. For further information
           on supported disk images, see systemd-nspawn(1)'s switch of the same name.

           Takes a journal namespace identifier string as argument. If not specified the data
           collected by the default namespace is shown. If specified shows the log data of the
           specified namespace instead. If the namespace is specified as "*" data from all
           namespaces is shown, interleaved. If the namespace identifier is prefixed with "+"
           data from the specified namespace and the default namespace is shown, interleaved, but
           no other. For details about journal namespaces see systemd-journald.service(8).


       The following options control how to filter journal records:

       -S, --since=, -U, --until=
           Start showing entries on or newer than the specified date, or on or older than the
           specified date, respectively. Date specifications should be of the format "2012-10-30
           18:17:16". If the time part is omitted, "00:00:00" is assumed. If only the seconds
           component is omitted, ":00" is assumed. If the date component is omitted, the current
           day is assumed. Alternatively the strings "yesterday", "today", "tomorrow" are
           understood, which refer to 00:00:00 of the day before the current day, the current
           day, or the day after the current day, respectively.  "now" refers to the current
           time. Finally, relative times may be specified, prefixed with "-" or "+", referring to
           times before or after the current time, respectively. For complete time and date
           specification, see systemd.time(7). Note that --output=short-full prints timestamps
           that follow precisely this format.

       -c, --cursor=
           Start showing entries from the location in the journal specified by the passed cursor.

           Start showing entries from the location in the journal after the location specified by
           the passed cursor. The cursor is shown when the --show-cursor option is used.

           If FILE exists and contains a cursor, start showing entries after this location.
           Otherwise show entries according to the other given options. At the end, write the
           cursor of the last entry to FILE. Use this option to continually read the journal by
           sequentially calling journalctl.

       -b [[ID][┬▒offset]|all], --boot[=[ID][┬▒offset]|all]
           Show messages from a specific boot. This will add a match for "_BOOT_ID=".

           The argument may be empty, in which case logs for the current boot will be shown.

           If the boot ID is omitted, a positive offset will look up the boots starting from the
           beginning of the journal, and an equal-or-less-than zero offset will look up boots
           starting from the end of the journal. Thus, 1 means the first boot found in the
           journal in chronological order, 2 the second and so on; while -0 is the last boot, -1
           the boot before last, and so on. An empty offset is equivalent to specifying -0,
           except when the current boot is not the last boot (e.g. because --directory was
           specified to look at logs from a different machine).

           If the 32-character ID is specified, it may optionally be followed by offset which
           identifies the boot relative to the one given by boot ID. Negative values mean earlier
           boots and positive values mean later boots. If offset is not specified, a value of
           zero is assumed, and the logs for the boot given by ID are shown.

           The special argument all can be used to negate the effect of an earlier use of -b.

       -u, --unit=UNIT|PATTERN
           Show messages for the specified systemd unit UNIT (such as a service unit), or for any
           of the units matched by PATTERN. If a pattern is specified, a list of unit names found
           in the journal is compared with the specified pattern and all that match are used. For
           each unit name, a match is added for messages from the unit ("_SYSTEMD_UNIT=UNIT"),
           along with additional matches for messages from systemd and messages about coredumps
           for the specified unit. A match is also added for "_SYSTEMD_SLICE=UNIT", such that if
           the provided UNIT is a systemd.slice(5) unit, all logs of children of the slice will
           be shown.

           With --user, all --unit arguments will be converted to match user messages as if
           specified with --user-unit.

           This parameter can be specified multiple times.

           Show messages for the specified user session unit. This will add a match for messages
           from the unit ("_SYSTEMD_USER_UNIT=" and "_UID=") and additional matches for messages
           from session systemd and messages about coredumps for the specified unit. A match is
           also added for "_SYSTEMD_USER_SLICE=UNIT", such that if the provided UNIT is a
           systemd.slice(5) unit, all logs of children of the unit will be shown.

           This parameter can be specified multiple times.

       -t, --identifier=SYSLOG_IDENTIFIER
           Show messages for the specified syslog identifier SYSLOG_IDENTIFIER.

           This parameter can be specified multiple times.

       -p, --priority=
           Filter output by message priorities or priority ranges. Takes either a single numeric
           or textual log level (i.e. between 0/"emerg" and 7/"debug"), or a range of
           numeric/text log levels in the form FROM..TO. The log levels are the usual syslog log
           levels as documented in syslog(3), i.e.  "emerg" (0), "alert" (1), "crit" (2),
           "err" (3), "warning" (4), "notice" (5), "info" (6), "debug" (7). If a single log level
           is specified, all messages with this log level or a lower (hence more important) log
           level are shown. If a range is specified, all messages within the range are shown,
           including both the start and the end value of the range. This will add "PRIORITY="
           matches for the specified priorities.

           Filter output by syslog facility. Takes a comma-separated list of numbers or facility
           names. The names are the usual syslog facilities as documented in syslog(3).
           --facility=help may be used to display a list of known facility names and exit.

       -g, --grep=
           Filter output to entries where the MESSAGE= field matches the specified regular
           expression. PERL-compatible regular expressions are used, see pcre2pattern(3) for a
           detailed description of the syntax.

           If the pattern is all lowercase, matching is case insensitive. Otherwise, matching is
           case sensitive. This can be overridden with the --case-sensitive option, see below.

           Make pattern matching case sensitive or case insensitive.

       -k, --dmesg
           Show only kernel messages. This implies -b and adds the match "_TRANSPORT=kernel".


       The following options control how journal records are printed:

       -o, --output=
           Controls the formatting of the journal entries that are shown. Takes one of the
           following options:

               is the default and generates an output that is mostly identical to the formatting
               of classic syslog files, showing one line per journal entry.

               is very similar, but shows timestamps in the format the --since= and --until=
               options accept. Unlike the timestamp information shown in short output mode this
               mode includes weekday, year and timezone information in the output, and is

               is very similar, but shows ISO 8601 wallclock timestamps.

               as for short-iso but includes full microsecond precision.

               is very similar, but shows classic syslog timestamps with full microsecond

               is very similar, but shows monotonic timestamps instead of wallclock timestamps.

               as for short-monotonic but includes the time difference to the previous entry.
               Maybe unreliable time differences are marked by a "*".

               is very similar, but shows seconds passed since January 1st 1970 UTC instead of
               wallclock timestamps ("UNIX time"). The time is shown with microsecond accuracy.

               shows the full-structured entry items with all fields.

               serializes the journal into a binary (but mostly text-based) stream suitable for
               backups and network transfer (see Journal Export Format[2] for more information).
               To import the binary stream back into native journald format use systemd-journal-

               formats entries as JSON objects, separated by newline characters (see Journal JSON
               Format[3] for more information). Field values are generally encoded as JSON
               strings, with three exceptions:

                1. Fields larger than 4096 bytes are encoded as null values. (This may be turned
                   off by passing --all, but be aware that this may allocate overly long JSON

                2. Journal entries permit non-unique fields within the same log entry. JSON does
                   not allow non-unique fields within objects. Due to this, if a non-unique field
                   is encountered a JSON array is used as field value, listing all field values
                   as elements.

                3. Fields containing non-printable or non-UTF8 bytes are encoded as arrays
                   containing the raw bytes individually formatted as unsigned numbers.

               Note that this encoding is reversible (with the exception of the size limit).

               formats entries as JSON data structures, but formats them in multiple lines in
               order to make them more readable by humans.

               formats entries as JSON data structures, but wraps them in a format suitable for
               Server-Sent Events[4].

               formats entries as JSON data structures, but prefixes them with an ASCII Record
               Separator character (0x1E) and suffixes them with an ASCII Line Feed character
               (0x0A), in accordance with JavaScript Object Notation (JSON) Text Sequences[5]

               generates a very terse output, only showing the actual message of each journal
               entry with no metadata, not even a timestamp. If combined with the
               --output-fields= option will output the listed fields for each log record, instead
               of the message.

               similar to short-full, but prefixes the unit and user unit names instead of the
               traditional syslog identifier. Useful when using templated instances, as it will
               include the arguments in the unit names.

           A comma separated list of the fields which should be included in the output. This has
           an effect only for the output modes which would normally show all fields (verbose,
           export, json, json-pretty, json-sse and json-seq), as well as on cat. For the former,
           the "__CURSOR", "__REALTIME_TIMESTAMP", "__MONOTONIC_TIMESTAMP", and "_BOOT_ID" fields
           are always printed.

       -n, --lines=
           Show the most recent journal events and limit the number of events shown. If --follow
           is used, this option is implied. The argument is a positive integer or "all" to
           disable line limiting. The default value is 10 if no argument is given.

       -r, --reverse
           Reverse output so that the newest entries are displayed first.

           The cursor is shown after the last entry after two dashes:

               -- cursor: s=0639...

           The format of the cursor is private and subject to change.

           Express time in Coordinated Universal Time (UTC).

       -x, --catalog
           Augment log lines with explanation texts from the message catalog. This will add
           explanatory help texts to log messages in the output where this is available. These
           short help texts will explain the context of an error or log event, possible
           solutions, as well as pointers to support forums, developer documentation, and any
           other relevant manuals. Note that help texts are not available for all messages, but
           only for selected ones. For more information on the message catalog, please refer to
           the Message Catalog Developer Documentation[6].

           Note: when attaching journalctl output to bug reports, please do not use -x.

           Don't show the hostname field of log messages originating from the local host. This
           switch has an effect only on the short family of output modes (see above).

           Note: this option does not remove occurrences of the hostname from log entries
           themselves, so it does not prevent the hostname from being visible in the logs.

       --no-full, --full, -l
           Ellipsize fields when they do not fit in available columns. The default is to show
           full fields, allowing them to wrap or be truncated by the pager, if one is used.

           The old options -l/--full are not useful anymore, except to undo --no-full.

       -a, --all
           Show all fields in full, even if they include unprintable characters or are very long.
           By default, fields with unprintable characters are abbreviated as "blob data". (Note
           that the pager may escape unprintable characters again.)

       -f, --follow
           Show only the most recent journal entries, and continuously print new entries as they
           are appended to the journal.

           Show all stored output lines, even in follow mode. Undoes the effect of --lines=.

       -q, --quiet
           Suppresses all informational messages (i.e. "-- Journal begins at ...", "-- Reboot
           --"), any warning messages regarding inaccessible system journals when run as a normal


       The following options control page support:

           Do not pipe output into a pager.

       -e, --pager-end
           Immediately jump to the end of the journal inside the implied pager tool. This implies
           -n1000 to guarantee that the pager will not buffer logs of unbounded size. This may be
           overridden with an explicit -n with some other numeric value, while -nall will disable
           this cap. Note that this option is only supported for the less(1) pager.


       The following options make be used together with the --setup-keys command, see below.

           Specifies the change interval for the sealing key when generating an FSS key pair with
           --setup-keys. Shorter intervals increase CPU consumption but shorten the time range of
           undetectable journal alterations. Defaults to 15min.

           Specifies the FSS verification key to use for the --verify operation.

           When --setup-keys is passed and Forward Secure Sealing (FSS) has already been
           configured, recreate FSS keys.


       The following commands are understood. If none is specified the default is to display
       journal records.

       -N, --fields
           Print all field names currently used in all entries of the journal.

       -F, --field=
           Print all possible data values the specified field can take in all entries of the

           Show a tabular list of boot numbers (relative to the current boot), their IDs, and the
           timestamps of the first and last message pertaining to the boot.

           Shows the current disk usage of all journal files. This shows the sum of the disk
           usage of all archived and active journal files.

       --vacuum-size=, --vacuum-time=, --vacuum-files=
           Removes the oldest archived journal files until the disk space they use falls below
           the specified size (specified with the usual "K", "M", "G" and "T" suffixes), or all
           archived journal files contain no data older than the specified timespan (specified
           with the usual "s", "m", "h", "days", "months", "weeks" and "years" suffixes), or no
           more than the specified number of separate journal files remain. Note that running
           --vacuum-size= has only an indirect effect on the output shown by --disk-usage, as the
           latter includes active journal files, while the vacuuming operation only operates on
           archived journal files. Similarly, --vacuum-files= might not actually reduce the
           number of journal files to below the specified number, as it will not remove active
           journal files.

           --vacuum-size=, --vacuum-time= and --vacuum-files= may be combined in a single
           invocation to enforce any combination of a size, a time and a number of files limit on
           the archived journal files. Specifying any of these three parameters as zero is
           equivalent to not enforcing the specific limit, and is thus redundant.

           These three switches may also be combined with --rotate into one command. If so, all
           active files are rotated first, and the requested vacuuming operation is executed
           right after. The rotation has the effect that all currently active files are archived
           (and potentially new, empty journal files opened as replacement), and hence the
           vacuuming operation has the greatest effect as it can take all log data written so far
           into account.

           Check the journal file for internal consistency. If the file has been generated with
           FSS enabled and the FSS verification key has been specified with --verify-key=,
           authenticity of the journal file is verified.

           Asks the journal daemon to write all yet unwritten journal data to the backing file
           system and synchronize all journals. This call does not return until the
           synchronization operation is complete. This command guarantees that any log messages
           written before its invocation are safely stored on disk at the time it returns.

           Asks the journal daemon for the reverse operation to --flush: if requested the daemon
           will write further log data to /run/log/journal/ and stops writing to
           /var/log/journal/. A subsequent call to --flush causes the log output to switch back
           to /var/log/journal/, see above.

           Similar to --relinquish-var, but executes no operation if the root file system and
           /var/lib/journal/ reside on the same mount point. This operation is used during system
           shutdown in order to make the journal daemon stop writing data to /var/log/journal/ in
           case that directory is located on a mount point that needs to be unmounted.

           Asks the journal daemon to flush any log data stored in /run/log/journal/ into
           /var/log/journal/, if persistent storage is enabled. This call does not return until
           the operation is complete. Note that this call is idempotent: the data is only flushed
           from /run/log/journal/ into /var/log/journal/ once during system runtime (but see
           --relinquish-var below), and this command exits cleanly without executing any
           operation if this has already happened. This command effectively guarantees that all
           data is flushed to /var/log/journal/ at the time it returns.

           Asks the journal daemon to rotate journal files. This call does not return until the
           rotation operation is complete. Journal file rotation has the effect that all
           currently active journal files are marked as archived and renamed, so that they are
           never written to in future. New (empty) journal files are then created in their place.
           This operation may be combined with --vacuum-size=, --vacuum-time= and --vacuum-file=
           into a single command, see above.

           Instead of showing journal contents, show internal header information of the journal
           fields accessed.

           This option is particularly useful when trying to identify out-of-order journal
           entries, as happens for example when the machine is booted with the wrong system time.

       --list-catalog [128-bit-ID...]
           List the contents of the message catalog as a table of message IDs, plus their short
           description strings.

           If any 128-bit-IDs are specified, only those entries are shown.

       --dump-catalog [128-bit-ID...]
           Show the contents of the message catalog, with entries separated by a line consisting
           of two dashes and the ID (the format is the same as .catalog files).

           If any 128-bit-IDs are specified, only those entries are shown.

           Update the message catalog index. This command needs to be executed each time new
           catalog files are installed, removed, or updated to rebuild the binary catalog index.

           Instead of showing journal contents, generate a new key pair for Forward Secure
           Sealing (FSS). This will generate a sealing key and a verification key. The sealing
           key is stored in the journal data directory and shall remain on the host. The
           verification key should be stored externally. Refer to the Seal= option in
           journald.conf(5) for information on Forward Secure Sealing and for a link to a
           refereed scholarly paper detailing the cryptographic theory it is based on.

       -h, --help
           Print a short help text and exit.

           Print a short version string and exit.


       On success, 0 is returned; otherwise, a non-zero failure code is returned.


           The maximum log level of emitted messages (messages with a higher log level, i.e. less
           important ones, will be suppressed). Either one of (in order of decreasing importance)
           emerg, alert, crit, err, warning, notice, info, debug, or an integer in the range
           0...7. See syslog(3) for more information.

           A boolean. If true, messages written to the tty will be colored according to priority.

           This setting is only useful when messages are written directly to the terminal,
           because journalctl(1) and other tools that display logs will color messages based on
           the log level on their own.

           A boolean. If true, console log messages will be prefixed with a timestamp.

           This setting is only useful when messages are written directly to the terminal or a
           file, because journalctl(1) and other tools that display logs will attach timestamps
           based on the entry metadata on their own.

           A boolean. If true, messages will be prefixed with a filename and line number in the
           source code where the message originates.

           Note that the log location is often attached as metadata to journal entries anyway.
           Including it directly in the message text can nevertheless be convenient when
           debugging programs.

           A boolean. If true, messages will be prefixed with the current numerical thread ID

           Note that the this information is attached as metadata to journal entries anyway.
           Including it directly in the message text can nevertheless be convenient when
           debugging programs.

           The destination for log messages. One of console (log to the attached tty),
           console-prefixed (log to the attached tty but with prefixes encoding the log level and
           "facility", see syslog(3), kmsg (log to the kernel circular log buffer), journal (log
           to the journal), journal-or-kmsg (log to the journal if available, and to kmsg
           otherwise), auto (determine the appropriate log target automatically, the default),
           null (disable log output).

           Pager to use when --no-pager is not given; overrides $PAGER. If neither $SYSTEMD_PAGER
           nor $PAGER are set, a set of well-known pager implementations are tried in turn,
           including less(1) and more(1), until one is found. If no pager implementation is
           discovered no pager is invoked. Setting this environment variable to an empty string
           or the value "cat" is equivalent to passing --no-pager.

           Note: if $SYSTEMD_PAGERSECURE is not set, $SYSTEMD_PAGER (as well as $PAGER) will be
           silently ignored.

           Override the options passed to less (by default "FRSXMK").

           Users might want to change two options in particular:

               This option instructs the pager to exit immediately when Ctrl+C is pressed. To
               allow less to handle Ctrl+C itself to switch back to the pager command prompt,
               unset this option.

               If the value of $SYSTEMD_LESS does not include "K", and the pager that is invoked
               is less, Ctrl+C will be ignored by the executable, and needs to be handled by the

               This option instructs the pager to not send termcap initialization and
               deinitialization strings to the terminal. It is set by default to allow command
               output to remain visible in the terminal even after the pager exits. Nevertheless,
               this prevents some pager functionality from working, in particular paged output
               cannot be scrolled with the mouse.

           See less(1) for more discussion.

           Override the charset passed to less (by default "utf-8", if the invoking terminal is
           determined to be UTF-8 compatible).

           Takes a boolean argument. When true, the "secure" mode of the pager is enabled; if
           false, disabled. If $SYSTEMD_PAGERSECURE is not set at all, secure mode is enabled if
           the effective UID is not the same as the owner of the login session, see geteuid(2)
           and sd_pid_get_owner_uid(3). In secure mode, LESSSECURE=1 will be set when invoking
           the pager, and the pager shall disable commands that open or create new files or start
           new subprocesses. When $SYSTEMD_PAGERSECURE is not set at all, pagers which are not
           known to implement secure mode will not be used. (Currently only less(1) implements
           secure mode.)

           Note: when commands are invoked with elevated privileges, for example under sudo(8) or
           pkexec(1), care must be taken to ensure that unintended interactive features are not
           enabled. "Secure" mode for the pager may be enabled automatically as describe above.
           Setting SYSTEMD_PAGERSECURE=0 or not removing it from the inherited environment allows
           the user to invoke arbitrary commands. Note that if the $SYSTEMD_PAGER or $PAGER
           variables are to be honoured, $SYSTEMD_PAGERSECURE must be set too. It might be
           reasonable to completely disable the pager using --no-pager instead.

           Takes a boolean argument. When true, systemd and related utilities will use colors in
           their output, otherwise the output will be monochrome. Additionally, the variable can
           take one of the following special values: "16", "256" to restrict the use of colors to
           the base 16 or 256 ANSI colors, respectively. This can be specified to override the
           automatic decision based on $TERM and what the console is connected to.

           The value must be a boolean. Controls whether clickable links should be generated in
           the output for terminal emulators supporting this. This can be specified to override
           the decision that systemd makes based on $TERM and other conditions.


       Without arguments, all collected logs are shown unfiltered:


       With one match specified, all entries with a field matching the expression are shown:

           journalctl _SYSTEMD_UNIT=avahi-daemon.service
           journalctl _SYSTEMD_CGROUP=/user.slice/user-42.slice/session-c1.scope

       If two different fields are matched, only entries matching both expressions at the same
       time are shown:

           journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097

       If two matches refer to the same field, all entries matching either expression are shown:

           journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service

       If the separator "+" is used, two expressions may be combined in a logical OR. The
       following will show all messages from the Avahi service process with the PID 28097 plus
       all messages from the D-Bus service (from any of its processes):

           journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service

       To show all fields emitted by a unit and about the unit, option -u/--unit= should be used.
       journalctl -u name expands to a complex filter similar to

             + UNIT=name.service _PID=1
             + OBJECT_SYSTEMD_UNIT=name.service _UID=0
             + COREDUMP_UNIT=name.service _UID=0 MESSAGE_ID=fc2e22bc6ee647b6b90729ab34a250b1

       (see systemd.journal-fields(7) for an explanation of those patterns).

       Show all logs generated by the D-Bus executable:

           journalctl /usr/bin/dbus-daemon

       Show all kernel logs from previous boot:

           journalctl -k -b -1

       Show a live log display from a system service apache.service:

           journalctl -f -u apache


       systemd(1), systemd-journald.service(8), systemctl(1), coredumpctl(1), systemd.journal-
       fields(7), journald.conf(5), systemd.time(7), systemd-journal-remote.service(8), systemd-


        1. Discoverable Partitions Specification

        2. Journal Export Format

        3. Journal JSON Format

        4. Server-Sent Events

        5. JavaScript Object Notation (JSON) Text Sequences

        6. Message Catalog Developer Documentation