JOURNALCTL(1) journalctl JOURNALCTL(1)
NAME
journalctl - Print log entries from the systemd journal
SYNOPSIS
journalctl [OPTIONS...] [MATCHES...]
DESCRIPTION
journalctl is used to print the log entries stored in the journal by
systemd-journald.service(8) and systemd-journal-remote.service(8).
If called without parameters, it will show the contents of the journal
accessible to the calling user, 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
--header option can be used to identify which files are being shown.
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 WARNING are
colored yellow; lines of level NOTICE are highlighted; lines of level
INFO are displayed normally; lines of level DEBUG are colored grey.
To write entries to the journal, a few methods may be used. In general,
output from systemd units is automatically connected to the journal, see
systemd-journald.service(8). In addition, systemd-cat(1) may be used to
send messages to the journal directly.
SOURCE OPTIONS
The following options control where to read journal records from:
--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.
The --user option affects how --unit= arguments are treated. See
--unit=.
Note that --user only works if persistent logging is enabled, via
the Storage= setting in journald.conf(5).
Added in version 205.
-M, --machine=
Show messages from a running, local container. Specify a container
name to connect to.
Added in version 209.
-m, --merge
Show entries interleaved from all available journals, including
remote ones.
Added in version 190.
-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.
Added in version 187.
-i GLOB, --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.
Added in version 205.
--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).
Added in version 201.
--image=IMAGE
Takes a path to a disk image file or block device node. If
specified, journalctl will operate on the file system in the
indicated disk image. This option is similar to --root=, but
operates on file systems stored in disk images or block devices,
thus providing an easy way to extract log data from disk images. The
disk image should either contain just a file system or a set of file
systems within a GPT partition table, following the Discoverable
Partitions Specification[1]. For further information on supported
disk images, see systemd-nspawn(1)'s switch of the same name.
Added in version 247.
--image-policy=policy
Takes an image policy string as argument, as per systemd.image-
policy(7). The policy is enforced when operating on the disk image
specified via --image=, see above. If not specified, defaults to the
"*" policy, i.e. all recognized file systems in the image are used.
--namespace=NAMESPACE
Takes a journal namespace identifier string as argument. If not
specified, the data collected by the default namespace is shown. If
specified, shows the log data of the specified namespace instead. If
the namespace is specified as "*" data from all namespaces is shown,
interleaved. If the namespace identifier is prefixed with "+" data
from the specified namespace and the default namespace is shown,
interleaved, but no other. For details about journal namespaces see
systemd-journald.service(8).
Added in version 245.
FILTERING OPTIONS
The following options control how to filter journal records:
-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.
Added in version 195.
-c, --cursor=
Start showing entries from the location in the journal specified by
the passed cursor.
Added in version 193.
--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.
Added in version 206.
--cursor-file=FILE
If FILE exists and contains a cursor, start showing entries after
this location. Otherwise, show entries according to the other given
options. At the end, write the cursor of the last entry to FILE. Use
this option to continually read the journal by sequentially calling
journalctl.
Added in version 242.
-b [[ID][±offset]|all], --boot[=[ID][±offset]|all]
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.
The special argument all can be used to negate the effect of an
earlier use of -b.
Added in version 186.
-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. A
match is also added for "_SYSTEMD_SLICE=UNIT", such that if the
provided UNIT is a systemd.slice(5) unit, all logs of children of
the slice will be shown.
With --user, all --unit= arguments will be converted to match user
messages as if specified with --user-unit=.
This parameter can be specified multiple times.
Added in version 195.
--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. A match is also
added for "_SYSTEMD_USER_SLICE=UNIT", such that if the provided UNIT
is a systemd.slice(5) unit, all logs of children of the unit will be
shown.
This parameter can be specified multiple times.
Added in version 198.
-I, --invocation=ID[±offset]|offset
Show messages from a specific invocation of unit. This will add a
match for "_SYSTEMD_INVOCATION_ID=",
"OBJECT_SYSTEMD_INVOCATION_ID=", "INVOCATION_ID=",
"USER_INVOCATION_ID=".
A positive offset will look up the invocations of a systemd unit
from the beginning of the journal, and zero or a negative offset
will look up invocations starting from the end of the journal. Thus,
1 means the first invocation found in the journal in chronological
order, 2 the second and so on; while 0 is the latest invocation, -1
the invocation before the latest, and so on.
If the 32-character ID is specified, it may optionally be followed
by ±offset which identifies the invocation relative to the one given
by invocation ID. Negative values mean earlier invocations and
positive values mean later invocations. If ±offset is not specified,
a value of zero is assumed, and the logs for the invocation given by
ID will be shown.
-I is equivalent to --invocation=0, and logs for the latest
invocation will be shown.
When an offset is specified, a unit name must be specified with
-u/--unit= or --user-unit= option.
When specified with -b/--boot=, then invocations are searched within
the specified boot.
Added in version 257.
-t, --identifier=SYSLOG_IDENTIFIER
Show messages for the specified syslog identifier SYSLOG_IDENTIFIER.
This parameter can be specified multiple times.
Added in version 217.
-T, --exclude-identifier=SYSLOG_IDENTIFIER
Exclude messages for the specified syslog identifier
SYSLOG_IDENTIFIER.
This parameter can be specified multiple times.
Added in version 256.
-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.
Added in version 188.
--facility=
Filter output by syslog facility. Takes a comma-separated list of
numbers or facility names. The names are the usual syslog facilities
as documented in syslog(3). --facility=help may be used to display
a list of known facility names and exit.
Added in version 245.
-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.
When used with --lines= (not prefixed with "+"), --reverse is
implied.
Added in version 237.
--case-sensitive[=BOOLEAN]
Make pattern matching case sensitive or case insensitive.
Added in version 237.
-k, --dmesg
Show only kernel messages. This implies -b and adds the match
"_TRANSPORT=kernel".
Added in version 205.
OUTPUT OPTIONS
The following options control how journal records are printed:
-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.
Added in version 206.
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.
Added in version 232.
short-iso
is very similar, but shows timestamps in the RFC 3339[2] profile
of ISO 8601.
Added in version 206.
short-iso-precise
as for short-iso but includes full microsecond precision.
Added in version 234.
short-precise
is very similar, but shows classic syslog timestamps with full
microsecond precision.
Added in version 207.
short-monotonic
is very similar, but shows monotonic timestamps instead of
wallclock timestamps.
Added in version 206.
short-delta
as for short-monotonic but includes the time difference to the
previous entry. Maybe unreliable time differences are marked by
a "*".
Added in version 252.
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.
Added in version 230.
verbose
shows the full-structured entry items with all fields.
Added in version 206.
export
serializes the journal into a binary (but mostly text-based)
stream suitable for backups and network transfer (see Journal
Export Format[3] for more information). To import the binary
stream back into native journald format use systemd-journal-
remote(8).
Added in version 206.
json
formats entries as JSON objects, separated by newline characters
(see Journal JSON Format[4] 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).
Added in version 206.
json-pretty
formats entries as JSON data structures, but formats them in
multiple lines in order to make them more readable by humans.
Added in version 206.
json-sse
formats entries as JSON data structures, but wraps them in a
format suitable for Server-Sent Events[5].
Added in version 206.
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[6]
("application/json-seq").
Added in version 240.
cat
generates a very terse output, only showing the actual message
of each journal entry with no metadata, not even a timestamp. If
combined with the --output-fields= option will output the listed
fields for each log record, instead of the message.
Added in version 206.
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.
Added in version 239.
--truncate-newline
Truncate each log message at the first newline character on output,
so that only the first line of each message is displayed.
Added in version 254.
--output-fields=
A comma separated list of the fields which should be included in the
output. This has an effect only for the output modes which would
normally show all fields (verbose, export, json, json-pretty,
json-sse and json-seq), as well as on cat. For the former, the
"__CURSOR", "__REALTIME_TIMESTAMP", "__MONOTONIC_TIMESTAMP", and
"_BOOT_ID" fields are always printed.
Added in version 236.
-n, --lines=
Show the most recent journal events and limit the number of events
shown. The argument is a positive integer or "all" to disable the
limit. Additionally, if the number is prefixed with "+", the oldest
journal events are used instead. The default value is 10 if no
argument is given.
If --follow is used, this option is implied. When not prefixed with
"+" and used with --grep=, --reverse is implied.
-r, --reverse
Reverse output so that the newest entries are displayed first.
Added in version 198.
--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.
Added in version 209.
--utc
Express time in Coordinated Universal Time (UTC).
Added in version 217.
-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, see Journal Message Catalogs[7].
Note: when attaching journalctl output to bug reports, please do not
use -x.
Added in version 196.
--no-hostname
Do not show the hostname field of log messages originating from the
local host. This switch has an effect only on the short family of
output modes (see above).
Note: this option does not remove occurrences of the hostname from
log entries themselves, so it does not prevent the hostname from
being visible in the logs.
Added in version 230.
--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.
Added in version 196.
-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.
--no-tail
Show all stored output lines, even in follow mode. Undoes the effect
of --lines=.
-q, --quiet
Suppresses all informational messages (i.e. "-- Journal begins at
...", "-- Reboot --"), any warning messages regarding inaccessible
system journals when run as a normal user.
PAGER CONTROL OPTIONS
The following options control page support:
--no-pager
Do not pipe output into a pager.
-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.
Added in version 198.
FORWARD SECURE SEALING (FSS) OPTIONS
The following options may be used together with the --setup-keys command
described below:
--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.
Added in version 189.
--verify-key=
Specifies the FSS verification key to use for the --verify
operation.
Added in version 189.
--force
When --setup-keys is passed and Forward Secure Sealing (FSS) has
already been configured, recreate FSS keys.
Added in version 206.
COMMANDS
The following commands are understood. If none is specified the default
is to display journal records:
-N, --fields
Print all field names currently used in all entries of the journal.
Added in version 229.
-F, --field=
Print all possible data values the specified field can take in all
entries of the journal.
Added in version 195.
--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. When specified with -n/--lines=[+]N option,
only the first (when the number prefixed with "+") or the last
(without prefix) N entries will be shown. When specified with
-r/--reverse, the list will be shown in the reverse order.
Added in version 209.
--list-invocations
List invocation IDs of a unit. Requires a unit name with -u/--unit=
or --user-unit=. Show a tabular list of invocation numbers (relative
to the current or latest invocation), their IDs, and the timestamps
of the first and last message pertaining to the invocation. When
-b/-boot is specified, invocations in the boot will be shown. When
specified with -n/--lines=[+]N option, only the first (when the
number prefixed with "+") or the last (without prefix) N entries
will be shown. When specified with -r/--reverse, the list will be
shown in the reverse order.
Added in version 257.
--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.
Added in version 190.
--vacuum-size=, --vacuum-time=, --vacuum-files=
--vacuum-size= removes the oldest archived journal files until the
disk space they use falls below the specified size. Accepts the
usual "K", "M", "G" and "T" suffixes (to the base of 1024).
--vacuum-time= removes archived journal files older than the
specified timespan. Accepts the usual "s" (default), "m", "h",
"days", "weeks", "months", and "years" suffixes, see systemd.time(7)
for details.
--vacuum-files= leaves only the specified number of separate journal
files.
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.
Added in version 218.
--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.
Added in version 189.
--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.
Added in version 228.
--relinquish-var
Asks the journal daemon for the reverse operation to --flush: if
requested the daemon will write further log data to
/run/log/journal/ and stops writing to /var/log/journal/. A
subsequent call to --flush causes the log output to switch back to
/var/log/journal/, see above.
Added in version 243.
--smart-relinquish-var
Similar to --relinquish-var, but executes no operation if the root
file system and /var/log/journal/ reside on the same mount point.
This operation is used during system shutdown in order to make the
journal daemon stop writing data to /var/log/journal/ in case that
directory is located on a mount point that needs to be unmounted.
Added in version 243.
--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
(but see --relinquish-var below), 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.
Added in version 217.
--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.
Added in version 227.
--header
Instead of showing journal contents, show internal header
information of the journal fields accessed.
This option is particularly useful when trying to identify
out-of-order journal entries, as happens for example when the
machine is booted with the wrong system time.
Added in version 187.
--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.
Added in version 196.
--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.
Added in version 199.
--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.
Added in version 196.
--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.
Added in version 189.
-h, --help
Print a short help text and exit.
--version
Print a short version string and exit.
EXIT STATUS
On success, 0 is returned; otherwise, a non-zero failure code is
returned.
ENVIRONMENT
$SYSTEMD_LOG_LEVEL
The maximum log level of emitted messages (messages with a higher
log level, i.e. less important ones, will be suppressed). Takes a
comma-separated list of values. A value may be either one of (in
order of decreasing importance) emerg, alert, crit, err, warning,
notice, info, debug, or an integer in the range 0...7. See syslog(3)
for more information. Each value may optionally be prefixed with one
of console, syslog, kmsg or journal followed by a colon to set the
maximum log level for that specific log target (e.g.
SYSTEMD_LOG_LEVEL=debug,console:info specifies to log at debug level
except when logging to the console which should be at info level).
Note that the global maximum log level takes priority over any per
target maximum log levels.
$SYSTEMD_LOG_COLOR
A boolean. If true, messages written to the tty will be colored
according to priority.
This setting is only useful when messages are written directly to
the terminal, because journalctl(1) and other tools that display
logs will color messages based on the log level on their own.
$SYSTEMD_LOG_TIME
A boolean. If true, console log messages will be prefixed with a
timestamp.
This setting is only useful when messages are written directly to
the terminal or a file, because journalctl(1) and other tools that
display logs will attach timestamps based on the entry metadata on
their own.
$SYSTEMD_LOG_LOCATION
A boolean. If true, messages will be prefixed with a filename and
line number in the source code where the message originates.
Note that the log location is often attached as metadata to journal
entries anyway. Including it directly in the message text can
nevertheless be convenient when debugging programs.
$SYSTEMD_LOG_TID
A boolean. If true, messages will be prefixed with the current
numerical thread ID (TID).
Note that the this information is attached as metadata to journal
entries anyway. Including it directly in the message text can
nevertheless be convenient when debugging programs.
$SYSTEMD_LOG_TARGET
The destination for log messages. One of console (log to the
attached tty), console-prefixed (log to the attached tty but with
prefixes encoding the log level and "facility", see syslog(3), kmsg
(log to the kernel circular log buffer), journal (log to the
journal), journal-or-kmsg (log to the journal if available, and to
kmsg otherwise), auto (determine the appropriate log target
automatically, the default), null (disable log output).
$SYSTEMD_LOG_RATELIMIT_KMSG
Whether to ratelimit kmsg or not. Takes a boolean. Defaults to
"true". If disabled, systemd will not ratelimit messages written to
kmsg.
$SYSTEMD_PAGER, $PAGER
Pager to use when --no-pager is not given. $SYSTEMD_PAGER is used
if set; otherwise $PAGER is used. If neither $SYSTEMD_PAGER nor
$PAGER are set, a set of well-known pager implementations is tried
in turn, including less(1) and more(1), until one is found. If no
pager implementation is discovered, no pager is invoked. Setting
those environment variables to an empty string or the value "cat" is
equivalent to passing --no-pager.
Note: if $SYSTEMD_PAGERSECURE is not set, $SYSTEMD_PAGER and $PAGER
can only be used to disable the pager (with "cat" or ""), and are
otherwise ignored.
$SYSTEMD_LESS
Override the options passed to less (by default "FRSXMK").
Users might want to change two options in particular:
K
This option instructs the pager to exit immediately when Ctrl+C
is pressed. To allow less to handle Ctrl+C itself to switch back
to the pager command prompt, unset this option.
If the value of $SYSTEMD_LESS does not include "K", and the
pager that is invoked is less, Ctrl+C will be ignored by the
executable, and needs to be handled by the pager.
X
This option instructs the pager to not send termcap
initialization and deinitialization strings to the terminal. It
is set by default to allow command output to remain visible in
the terminal even after the pager exits. Nevertheless, this
prevents some pager functionality from working, in particular
paged output cannot be scrolled with the mouse.
Note that setting the regular $LESS environment variable has no
effect for less invocations by systemd tools.
See less(1) for more discussion.
$SYSTEMD_LESSCHARSET
Override the charset passed to less (by default "utf-8", if the
invoking terminal is determined to be UTF-8 compatible).
Note that setting the regular $LESSCHARSET environment variable has
no effect for less invocations by systemd tools.
$SYSTEMD_PAGERSECURE
Common pager commands like less(1), in addition to "paging", i.e.
scrolling through the output, support opening of or writing to other
files and running arbitrary shell commands. When commands are
invoked with elevated privileges, for example under sudo(8) or
pkexec(1), the pager becomes a security boundary. Care must be taken
that only programs with strictly limited functionality are used as
pagers, and unintended interactive features like opening or creation
of new files or starting of subprocesses are not allowed. "Secure
mode" for the pager may be enabled as described below, if the pager
supports that (most pagers are not written in a way that takes this
into consideration). It is recommended to either explicitly enable
"secure mode" or to completely disable the pager using --no-pager or
PAGER=cat when allowing untrusted users to execute commands with
elevated privileges.
This option takes a boolean argument. When set to true, the "secure
mode" of the pager is enabled. In "secure mode", LESSSECURE=1 will
be set when invoking the pager, which instructs the pager to disable
commands that open or create new files or start new subprocesses.
Currently only less(1) is known to understand this variable and
implement "secure mode".
When set to false, no limitation is placed on the pager. Setting
SYSTEMD_PAGERSECURE=0 or not removing it from the inherited
environment may allow the user to invoke arbitrary commands.
When $SYSTEMD_PAGERSECURE is not set, systemd tools attempt to
automatically figure out if "secure mode" should be enabled and
whether the pager supports it. "Secure mode" is enabled if the
effective UID is not the same as the owner of the login session, see
geteuid(2) and sd_pid_get_owner_uid(3), or when running under
sudo(8) or similar tools ($SUDO_UID is set [8]). In those cases,
SYSTEMD_PAGERSECURE=1 will be set and pagers which are not known to
implement "secure mode" will not be used at all. Note that this
autodetection only covers the most common mechanisms to elevate
privileges and is intended as convenience. It is recommended to
explicitly set $SYSTEMD_PAGERSECURE or disable the pager.
Note that if the $SYSTEMD_PAGER or $PAGER variables are to be
honoured, other than to disable the pager, $SYSTEMD_PAGERSECURE must
be set too.
$SYSTEMD_COLORS
Takes a boolean argument. When true, systemd and related utilities
will use colors in their output, otherwise the output will be
monochrome. Additionally, the variable can take one of the following
special values: "16", "256" to restrict the use of colors to the
base 16 or 256 ANSI colors, respectively. This can be specified to
override the automatic decision based on $TERM and what the console
is connected to.
$SYSTEMD_URLIFY
The value must be a boolean. Controls whether clickable links should
be generated in the output for terminal emulators supporting this.
This can be specified to override the decision that systemd makes
based on $TERM and other conditions.
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
journalctl _SYSTEMD_CGROUP=/user.slice/user-42.slice/session-c1.scope
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
To show all fields emitted by a unit and about the unit, option
-u/--unit= should be used. journalctl -u name expands to a complex
filter similar to
_SYSTEMD_UNIT=name.service
+ UNIT=name.service _PID=1
+ OBJECT_SYSTEMD_UNIT=name.service _UID=0
+ COREDUMP_UNIT=name.service _UID=0 MESSAGE_ID=fc2e22bc6ee647b6b90729ab34a250b1
(see systemd.journal-fields(7) for an explanation of those patterns).
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-cat(1), systemd-journald.service(8), systemctl(1),
coredumpctl(1), systemd.journal-fields(7), journald.conf(5),
systemd.time(7), systemd-journal-remote.service(8), systemd-journal-
upload.service(8)
NOTES
1. Discoverable Partitions Specification
https://uapi-group.org/specifications/specs/discoverable_partitions_specification
2. RFC 3339
https://tools.ietf.org/html/rfc3339
3. Journal Export Format
https://systemd.io/JOURNAL_EXPORT_FORMATS#journal-export-format
4. Journal JSON Format
https://systemd.io/JOURNAL_EXPORT_FORMATS#journal-json-format
5. Server-Sent Events
https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events
6. JavaScript Object Notation (JSON) Text Sequences
https://tools.ietf.org/html/rfc7464
7. Journal Message Catalogs
https://systemd.io/CATALOG
8. It is recommended for other tools to set and check $SUDO_UID as
appropriate, treating it is a common interface.
systemd 257.9 JOURNALCTL(1)
Generated by dwww version 1.16 on Tue Dec 16 04:59:24 CET 2025.