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; lines of level DEBUG are colored lighter grey; 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. 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.
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 only has an effect for the output modes which
would normally show all fields (verbose, export, json,
json-pretty, json-sse and json-seq). 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 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[5].
Note: when attaching journalctl output to bug reports,
please do not use -x.
-q, --quiet
Suppresses all informational 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.
-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
insenstive.
-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:
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).
--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, 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. 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.
