Home : Computers : Linux : Man Pages : journalctl

journalctl


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 appears 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).

       As shortcuts for a few types of field/value matches, file paths may be
       specified. If a file path refers to an executable file, this is
       equivalent to an "_EXE=" match for the canonicalized binary path.
       Similarly, if a path refers to a device node then match is added for
       the kernel name of the device ("_KERNEL_DEVICE="). Also, matches for
       the kernel names of all the parent devices are added automatically.
       Device node paths are not stable across reboots, therefore match for
       the current boot id ("_BOOT_ID=") is always added as well. Note that
       only the log entries for the existing device nodes maybe queried by
       providing path to the device node.

       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 the "systemd-journal", "adm",
       and "wheel" groups 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
       --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-iso
               is very similar, but shows ISO 8601 wallclock timestamps.

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

       -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 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 a
           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
           pertaining to the boot.

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

       -t, --identifier=SYSLOG_IDENTIFIER|PATTERN
           Show messages for the specified syslog identifier
           SYSLOG_IDENTIFIER, or for any of the messages with a
           "SYSLOG_IDENTIFIER" matched by PATTERN.

           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.

       -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 this 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.

       -F, --field=
           Print all possible data values the specified field can take 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 catalog file hierarchy underneath the specified
           directory instead of the root directory (e.g.  --update-catalog
           will create ROOT/var/lib/systemd/catalog/database).

       --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 three 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=
           Removes archived journal files until the disk space they use falls
           below the specified size (specified with the usual "K", "M", "G",
           "T" suffixes), or all journal files contain no data older than the
           specified timespan (specified with the usual "s", "min", "h",
           "days", "months", "weeks", "years" suffixes). Note that running
           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.

       --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.

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

       --version
           Print a short version string and exit.

       --no-pager


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)


NOTES

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

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

        3. Server-Sent Events
Subscribe to us on YouTube