journalctl

journalctl -f

journalctl -b

journalctl -u <unit_name.service>

journalctl --since "2024-01-01 00:00:00"

journalctl --since "2024-01-01" --until "2024-01-02"

journalctl _PID=<PID>

journalctl _UID=<UID>

journalctl -p <PRIORITY>

journalctl --disk-usage

journalctl --vacuum-size=100M

journalctl --vacuum-time=2weeks

JOURNALCTL(1)                                            journalctl                                           JOURNALCTL(1)

NAME
       journalctl - Print log entries from the systemd journal

SYNOPSIS

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

DESCRIPTION
       journalctl is used to print the log entries stored in the journal by systemd-journald.service(8) and systemd-
       journal-remote.service(8).

       If called without parameters, it will show the contents of the journal accessible to the calling user, 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 WARNING are colored yellow; lines of level NOTICE are highlighted; lines of level INFO are displayed
       normally; lines of level DEBUG are colored grey.

       To write entries to the journal, a few methods may be used. In general, output from systemd units is automatically
       connected to the journal, see systemd-journald.service(8). In addition, systemd-cat(1) may be used to send messages
       to the journal directly.

SOURCE OPTIONS
       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=.

           Note that --user only works if persistent logging is enabled, via the Storage= setting in journald.conf(5).

           Added in version 205.

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

           Added in version 209.

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

           Added in version 190.

       -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 paths.

           Added in version 187.

       --file=GLOB
           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 interleaved.

           Added in version 205.

       --root=ROOT
           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).

           Added in version 201.

       --image=IMAGE
           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.

           Added in version 247.

       --image-policy=policy
           Takes an image policy string as argument, as per systemd.image-policy(7). The policy is enforced when operating
           on the disk image specified via --image=, see above. If not specified defaults to the "*" policy, i.e. all
           recognized file systems in the image are used.

       --namespace=NAMESPACE
           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).

           Added in version 245.

FILTERING OPTIONS
       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.

           Added in version 195.

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

           Added in version 193.

       --after-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.

           Added in version 206.

       --cursor-file=FILE
           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.

           Added in version 242.

       -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.

           Added in version 186.

       -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.

           Added in version 195.

       --user-unit=
           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.

           Added in version 198.

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

           This parameter can be specified multiple times.

           Added in version 217.

       -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.

           Added in version 188.

       --facility=
           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.

           Added in version 245.

       -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.

           When used with --lines= (not prefixed with "+"), --reverse is implied.

           Added in version 237.

       --case-sensitive[=BOOLEAN]
           Make pattern matching case sensitive or case insensitive.

           Added in version 237.

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

           Added in version 205.

OUTPUT OPTIONS
       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:

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

               Added in version 206.

           short-full
               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 locale-independent.

               Added in version 232.

           short-iso
               is very similar, but shows timestamps in the RFC 3339[2] profile of ISO 8601.

               Added in version 206.

           short-iso-precise
               as for short-iso but includes full microsecond precision.

               Added in version 234.

           short-precise
               is very similar, but shows classic syslog timestamps with full microsecond precision.

               Added in version 207.

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

               Added in version 206.

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

               Added in version 252.

           short-unix
               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.

               Added in version 230.

           verbose
               shows the full-structured entry items with all fields.

               Added in version 206.

           export
               serializes the journal into a binary (but mostly text-based) stream suitable for backups and network
               transfer (see Journal Export Format[3] for more information). To import the binary stream back into native
               journald format use systemd-journal-remote(8).

               Added in version 206.

           json
               formats entries as JSON objects, separated by newline characters (see Journal JSON Format[4] 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 objects.)

                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).

               Added in version 206.

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

               Added in version 206.

           json-sse
               formats entries as JSON data structures, but wraps them in a format suitable for Server-Sent Events[5].

               Added in version 206.

           json-seq
               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[6] ("application/json-seq").

               Added in version 240.

           cat
               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.

               Added in version 206.

           with-unit
               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.

               Added in version 239.

       --truncate-newline
           Truncate each log message at the first newline character on output, so that only the first line of each message
           is displayed.

           Added in version 254.

       --output-fields=
           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.

           Added in version 236.

       -n, --lines=
           Show the most recent journal events and limit the number of events shown. The argument is a positive integer or
           "all" to disable the limit. Additionally, if the number is prefixed with "+", the oldest journal events are used
           instead. The default value is 10 if no argument is given.

           If --follow is used, this option is implied. When not prefixed with "+" and used with --grep=, --reverse is
           implied.

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

           Added in version 198.

       --show-cursor
           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.

           Added in version 209.

       --utc
           Express time in Coordinated Universal Time (UTC).

           Added in version 217.

       -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[7].

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

           Added in version 196.

       --no-hostname
           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.

           Added in version 230.

       --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.

           Added in version 196.

       -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.

       --no-tail
           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 user.

PAGER CONTROL OPTIONS
       The following options control page support:

       --no-pager
           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.

           Added in version 198.

FORWARD SECURE SEALING (FSS) OPTIONS
       The following options may be used together with the --setup-keys command described below:

       --interval=
           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.

           Added in version 189.

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

           Added in version 189.

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

           Added in version 206.

COMMANDS
       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.

           Added in version 229.

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

           Added in version 195.

       --list-boots
           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.

           Added in version 209.

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

           Added in version 190.

       --vacuum-size=, --vacuum-time=, --vacuum-files=
           --vacuum-size= removes the oldest archived journal files until the disk space they use falls below the specified
           size. Accepts the usual "K", "M", "G" and "T" suffixes (to the base of 1024).

           --vacuum-time= removes archived journal files older than the specified timespan. Accepts the usual "s"
           (default), "m", "h", "days", "weeks", "months", and "years" suffixes, see systemd.time(7) for details.

           --vacuum-files= leaves only the specified number of separate journal files.

           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.

           Added in version 218.

       --verify
           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.

           Added in version 189.

       --sync
           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.

           Added in version 228.

       --relinquish-var
           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.

           Added in version 243.

       --smart-relinquish-var
           Similar to --relinquish-var, but executes no operation if the root file system and /var/log/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.

           Added in version 243.

       --flush
           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.

           Added in version 217.

       --rotate
           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.

           Added in version 227.

       --header
           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.

           Added in version 187.

       --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.

           Added in version 196.

       --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.

           Added in version 199.

       --update-catalog
           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.

           Added in version 196.

       --setup-keys
           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.

           Added in version 189.

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

       --version
           Print a short version string and exit.

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

ENVIRONMENT
       $SYSTEMD_LOG_LEVEL
           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.

       $SYSTEMD_LOG_COLOR
           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.

       $SYSTEMD_LOG_TIME
           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.

       $SYSTEMD_LOG_LOCATION
           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.

       $SYSTEMD_LOG_TID
           A boolean. If true, messages will be prefixed with the current numerical thread ID (TID).

           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.

       $SYSTEMD_LOG_TARGET
           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).

       $SYSTEMD_LOG_RATELIMIT_KMSG
           Whether to ratelimit kmsg or not. Takes a boolean. Defaults to "true". If disabled, systemd will not ratelimit
           messages written to kmsg.

       $SYSTEMD_PAGER
           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.

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

           Users might want to change two options in particular:

           K
               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 pager.

           X
               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.

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

       $SYSTEMD_PAGERSECURE
           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.

       $SYSTEMD_COLORS
           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.

       $SYSTEMD_URLIFY
           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.

EXAMPLES
       Without arguments, all collected logs are shown unfiltered:

           journalctl

       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

           _SYSTEMD_UNIT=name.service
             + 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

SEE ALSO
       systemd(1), systemd-cat(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-journal-upload.service(8)

NOTES
        1. Discoverable Partitions Specification
           https://uapi-group.org/specifications/specs/discoverable_partitions_specification

        2. RFC 3339
           https://tools.ietf.org/html/rfc3339

        3. Journal Export Format
           https://systemd.io/JOURNAL_EXPORT_FORMATS#journal-export-format

        4. Journal JSON Format
           https://systemd.io/JOURNAL_EXPORT_FORMATS#journal-json-format

        5. Server-Sent Events
           https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events

        6. JavaScript Object Notation (JSON) Text Sequences
           https://tools.ietf.org/html/rfc7464

        7. Message Catalog Developer Documentation
           https://www.freedesktop.org/wiki/Software/systemd/catalog

systemd 255                                                                                                   JOURNALCTL(1)