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).
-M, --machine=
Show messages from a running, local container. Specify a
container name to connect to.
-m, --merge
Show entries interleaved from all available journals,
including remote ones.
-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).
--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.
--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).
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.
-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.
--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.
-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.
-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.
--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.
-t, --identifier=SYSLOG_IDENTIFIER
Show messages for the specified syslog identifier
SYSLOG_IDENTIFIER.
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.
--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.
-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=, --reverse is implied.
--case-sensitive[=BOOLEAN]
Make pattern matching case sensitive or case
insensitive.
-k, --dmesg
Show only kernel messages. This implies -b and
adds the match "_TRANSPORT=kernel".
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.
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.
--truncate-newline
Truncate each log message at the first newline character
on output, so that only the first line of each message is displayed.
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-delta
as for short-monotonic but includes the time
difference to the previous entry. Maybe unreliable time differences are marked
by a "*".
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[2] 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[3] 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[4].
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[5]
("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. If
combined with the --output-fields= option will output the listed fields
for each log record, instead of the message.
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 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.
-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.
When used with --grep=, --reverse is implied.
-r, --reverse
Reverse output so that the newest entries are displayed
first.
--show-cursor
The cursor is shown after the last entry after two
dashes:
The format of the cursor is private and subject to change.
--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[6].
Note: when attaching journalctl output to bug reports,
please do not use -x.
--no-hostname
Don't 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.
--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.
--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.
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.
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.
--verify-key=
Specifies the FSS verification key to use for the
--verify operation.
--force
When --setup-keys is passed and Forward Secure
Sealing (FSS) has already been configured, recreate FSS keys.
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.
-F, --field=
Print all possible data values the specified field can
take in all entries of the journal.
--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.
--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=
--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", "months",
"weeks" 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.
--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.
--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.
--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.
--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.
--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.
--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.
--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.
--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.
-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). 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.
$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 to use when
--no-pager is not given;
overrides
$PAGER. If neither
$SYSTEMD_PAGER nor
$PAGER
are set, a set of well-known pager implementations are tried in turn,
including
less(1) and
more(1), until one is found. If no pager
implementation is discovered no pager is invoked. Setting this environment
variable to an empty string or the value "cat" is equivalent to
passing
--no-pager.
Note: if $SYSTEMD_PAGERSECURE is not set,
$SYSTEMD_PAGER (as well as $PAGER) will be silently
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
Takes a boolean argument. When true, the
"secure" mode of the pager is enabled; if false, disabled. If
$SYSTEMD_PAGERSECURE is not set at all, 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). In secure mode,
LESSSECURE=1 will be set when invoking the pager, and the pager shall
disable commands that open or create new files or start new subprocesses. When
$SYSTEMD_PAGERSECURE is not set at all, pagers which are not known to
implement secure mode will not be used. (Currently only
less(1)
implements secure mode.)
Note: when commands are invoked with elevated privileges, for
example under sudo(8) or pkexec(1), care must be taken to
ensure that unintended interactive features are not enabled.
"Secure" mode for the pager may be enabled automatically as
describe above. Setting SYSTEMD_PAGERSECURE=0 or not removing it from
the inherited environment allows the user to invoke arbitrary commands. Note
that if the $SYSTEMD_PAGER or $PAGER variables are to be
honoured, $SYSTEMD_PAGERSECURE must be set too. It might be
reasonable to completely disable the pager using --no-pager
instead.
$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:
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:
Show a live log display from a system service apache.service:
NOTES¶
- 1.
- Discoverable Partitions Specification
- 2.
- Journal Export Format
- 3.
- Journal JSON Format
- 4.
- Server-Sent Events
- 5.
- JavaScript Object Notation (JSON) Text Sequences
- 6.
- Message Catalog Developer Documentation
