journalctl(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | ENVIRONMENT | EXAMPLES | SEE ALSO | NOTES | COLOPHON

JOURNALCTL(1)                  journalctl                  JOURNALCTL(1)

NAME         top

       journalctl - Query the systemd journal

SYNOPSIS         top

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

DESCRIPTION         top

       journalctl may be used to query the contents of the systemd(1)
       journal as written by systemd-journald.service(8).

       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 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.

OPTIONS         top

       The following options are understood:

       --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.

       -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.

       -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.

       --no-tail
           Show all stored output lines, even in follow mode. Undoes the
           effect of --lines=.

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

       -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.

           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.

           short-iso
               is very similar, but shows ISO 8601 wallclock timestamps.

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

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

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

           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.

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

           export
               serializes the journal into a binary (but mostly
               text-based) stream suitable for backups and network
               transfer (see Journal Export Format[1] for more
               information). To import the binary stream back into
               native journald format use systemd-journal-remote(8).

           json
               formats entries as JSON objects, separated by newline
               characters (see Journal JSON Format[2] 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).

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

           json-sse
               formats entries as JSON data structures, but wraps them
               in a format suitable for Server-Sent Events[3].

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

           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.

           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.

       --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.

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

       --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.

       -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[5].

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

       -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.

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

       -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.

       --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.

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

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

           This parameter can be specified multiple times.

       -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.

           This parameter can be specified multiple times.

       --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.

       -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.

       --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.

       -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.

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

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

       --cursor-file=FILE
           If FILE exists and contains a cursor, start showing entries
           after this location. Otherwise the show entries according 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.

       --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.

       --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.

       -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.

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

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

       --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.

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

       -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.

       --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.

       --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).

       --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 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[6]. For further
           information on supported disk images, see systemd-nspawn(1)'s
           switch of the same name.

       --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).

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

       --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.

       --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.

       --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-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.

       --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.

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

       --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.

       --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.

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

       --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.

       --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.

       --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.

       --smart-relinquish-var
           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.

       --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.

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

       --version
           Print a short version string and exit.

       --no-pager
           Do not pipe output into a pager.

EXIT STATUS         top

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

ENVIRONMENT         top

       $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, 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_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.

       $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         top

       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         top

       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-journal-upload.service(8)

NOTES         top

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

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

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

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

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

        6. Discoverable Partitions Specification
           https://systemd.io/DISCOVERABLE_PARTITIONS

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 2021-04-01.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-04-01.)  If you discover 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 248                                                JOURNALCTL(1)

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