journalctl(1)



JOURNALCTL(1)                     journalctl                     JOURNALCTL(1)

NAME
       journalctl - Query the systemd journal

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

DESCRIPTION
       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; other lines are displayed normally.

OPTIONS
       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.

       -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 data structures, one per line (see
               Journal JSON Format[2] for more information).

           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].

           cat
               generates a very terse output, only showing the actual message
               of each journal entry with no metadata, not even a timestamp.

       --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 only has an effect on the short family of
           output modes (see above).

       -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[4].

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

       -q, --quiet
           Suppresses all info messages (i.e. "-- Logs begin 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], --boot=[ID][+-offset]
           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.

       --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.

           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.

           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.

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

       --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).

       --new-id128
           Instead of showing journal contents, generate a new 128-bit ID
           suitable for identifying messages. This is intended for usage by
           developers who need a new identifier for a new message they
           introduce and want to make recognizable. This will print the new ID
           in four different formats which can be copied into source code or
           similar.

       --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 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.

       --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,
           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.

       --rotate
           Asks the journal daemon to rotate journal files. This call does not
           return until the rotation operation is complete.

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

ENVIRONMENT
       $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").

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

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

       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

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

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

systemd 235                                                      JOURNALCTL(1)

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