CTL(1)
NAME
journalctl - Query the systemd journal
SYNOPSIS
journalctl [OPTIONS...] [MATCHES...]
DESCRIPTION
journalctl may be used to query the contents of the systemd(1) journal as written by systemd-
journald.service(8).
If called without 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
Manual page journalctl(1) line 1/650 5% (press h for help or q to quit)
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.
Manual page journalctl(1) line 22/650 8%
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.
Manual page journalctl(1) line 46/650 12%
-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.
Manual page journalctl(1) line 71/650 16%
-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
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
Manual page journalctl(1) line 122/650 2
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. 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 traditionall
onal
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.
--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 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.
-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. "-- Journal begins 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]|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.
--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. 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.
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.
-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.
--case-sensitive[=BOOLEAN]
Make pattern matching case sensitive or case insensitive.
-c, --cursor=
Start showing entries from the location in the journal specified by the passed cursor.
--cursor-file=FILE
If FILE exists and contains a cursor, start showing entries after this location. Otherwise the
show entries according 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.
--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:
-- cursor: s=0639...
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).
--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 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[6].
For further information on supported disk images, see systemd-nspawn(1)'s switch of the same
name.
--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).
--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 (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.
--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/lib/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.
--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.
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_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.
$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.
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).
$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:
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
So many issues !!