Ubuntu Manpage: journalctl - Query the systemd journal

name
synopsis
description
options
exit status
environment
examples
see also
notes

Provided by: systemd_204-5ubuntu20.31_amd64

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 parameter 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, if the character "+" appears as separate word on
the command line all matches before and after are 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. Similar, if a
path refers to a device node, this is equivalent to a _KERNEL_DEVICE= match for the device.

Output is interleaved from all accessible journal files, whether they are rotated or currently being
written, and regardless whether they belong to the system itself or are accessible user journals.

All users are granted access to their private per-user journals. However, by default only root and users
who are members of the adm group get access to the system journal and the journals of other users.

OPTIONS

The following options are understood:

-h, --help
Prints a short help text and exits.

--version
Prints a short version string and exits.

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

--full
Show all (printable) fields in 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 won't buffer logs of unbounded size. This may be overridden with an explicit
-n with some other numeric value on the command line. 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, a positive integer, is optional, and defaults to 10.

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

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

-o, --output=
Controls the formatting of the journal entries that are shown. Takes one of short, short-monotonic,
verbose, export, json, json-pretty, json-sse, cat. short is the default and generates an output that
is mostly identical to the formatting of classic syslog log files, showing one line per journal
entry. short-monotonic is very similar but shows monotonic timestamps instead of wallclock
timestamps. 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). json formats entries as JSON data structures, one
per line (see Journal JSON Format[2] for more information). json-pretty also formats entries as JSON
data structures, but formats them in multiple lines in order to make them more readable for humans.
json-sse also 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 meta data, not even a timestamp.

-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].

-q, --quiet
Suppresses any warning message regarding inaccessible system journals when run as normal user.

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

-b, --this-boot
Show data only from current boot. This will add a match for _BOOT_ID= for the current boot ID of the
kernel.

-u, --unit=
Show messages for the specified systemd unit. This will add a match for messages from the unit
(_SYSTEMD_UNIT=) and 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.

--since=, --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.

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

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

--root=ROOT
Takes a directory path as 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. 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.

--list-catalog [ID128...]
List the contents of the message catalog, as table of message IDs plus their short description
strings.

If any ID128s are specified, only those entries are shown.

--dump-catalog [ID128...]
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 ID128s 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.

--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.

EXIT STATUS

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

ENVIRONMENT

       $SYSTEMD_PAGER
           Pager to use when --no-pager is not given; overrides $PAGER. Setting this to an empty string or the
           value cat is equivalent to passing --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 logs of the kernel device node /dev/sda:

           journalctl /dev/sda

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

        4. Message Catalog Developer Documentation
           http://www.freedesktop.org/wiki/Software/systemd/catalog