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
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-iso
is very similar, but shows ISO 8601 wallclock
timestamps.
short-precise
is very similar, but shows timestamps with full
microsecond precision.
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
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
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 a 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|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:
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.
-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 --vacuum-size= has only indirect effect on the output shown by
--disk-usage as the latter includes active journal files, while the
former only operates on archived journal files. --vacuum-size= and
--vacuum-time= may be combined in a single invocation to enforce both a
size and time limit on the archived journal files.
--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.
--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
Do not pipe output into a pager.