busctl — Introspect the bus
busctl [OPTIONS...] [COMMAND] [NAME...]
The following commands are understood:
Show all peers on the bus, by their service
names. By default, shows both unique and well-known names, but
this may be changed with the --unique and
--acquired switches. This is the default
operation if no command is specified.
SERVICE]¶Show process information and credentials of a bus service (if one is specified by its unique or well-known name), a process (if one is specified by its numeric PID), or the owner of the bus (if no parameter is specified).
SERVICE...]¶Dump messages being exchanged. If
SERVICE is specified, show messages
to or from this peer, identified by its well-known or unique
name. Otherwise, show all messages on the bus. Use
Ctrl+C
to terminate the dump.
SERVICE...]¶Similar to monitor but writes the output in pcapng format (for details, see PCAP Next Generation (pcapng) Capture File Format). Make sure to redirect standard output to a file or pipe. Tools like wireshark(1) may be used to dissect and view the resulting files.
SERVICE...]¶Shows an object tree of one or more
services. If SERVICE is specified,
show object tree of the specified services only. Otherwise,
show all object trees of all services on the bus that acquired
at least one well-known name.
SERVICE OBJECT [INTERFACE]¶Show interfaces, methods, properties and signals of the specified object (identified by its path) on the specified service. If the interface argument is passed, the output is limited to members of the specified interface.
SERVICE OBJECT INTERFACE METHOD [SIGNATURE [ARGUMENT...]]¶Invoke a method and show the response. Takes a
service name, object path, interface name and method name. If
parameters shall be passed to the method call, a signature
string is required, followed by the arguments, individually
formatted as strings. For details on the formatting used, see
below. To suppress output of the returned data, use the
--quiet option.
OBJECT INTERFACE SIGNAL [SIGNATURE [ARGUMENT...]]¶Emit a signal. Takes an object path, interface name and method name. If parameters
shall be passed, a signature string is required, followed by the arguments, individually formatted as
strings. For details on the formatting used, see below. To specify the destination of the signal,
use the --destination= option.
SERVICE] OBJECT INTERFACE SIGNAL ¶Wait for a signal. Takes an object path, interface name, and signal name. To suppress
output of the returned data, use the --quiet option. The service name may be
omitted, in which case busctl will match signals from any sender.
SERVICE OBJECT INTERFACE PROPERTY... ¶Retrieve the current value of one or more
object properties. Takes a service name, object path,
interface name and property name. Multiple properties may be
specified at once, in which case their values will be shown one
after the other, separated by newlines. The output is, by
default, in terse format. Use --verbose for a
more elaborate output format.
SERVICE OBJECT INTERFACE PROPERTY SIGNATURE ARGUMENT... ¶Set the current value of an object property. Takes a service name, object path, interface name, property name, property signature, followed by a list of parameters formatted as strings.
Show command syntax help.
The following options are understood:
--address=ADDRESS¶Connect to the bus specified by
ADDRESS instead of using suitable
defaults for either the system or user bus (see
--system and --user
options).
--show-machine¶When showing the list of peers, show a column containing the names of containers they belong to. See systemd-machined.service(8).
--unique¶When showing the list of peers, show only
"unique" names (of the form
":").
number.number
--acquired¶The opposite of --unique —
only "well-known" names will be shown.
--activatable¶When showing the list of peers, show only peers which have actually not been activated yet, but may be started automatically if accessed.
--match=MATCH¶When showing messages being exchanged, show only the
subset matching MATCH.
See
sd_bus_add_match(3).
--size=¶When used with the capture command, specifies the maximum bus message size to capture ("snaplen"). Defaults to 4096 bytes.
--list¶When used with the tree command, shows a flat list of object paths instead of a tree.
-q, --quiet¶When used with the call command, suppresses display of the response message payload. Note that even if this option is specified, errors returned will still be printed and the tool will indicate success or failure with the process exit code.
--verbose¶When used with the call or get-property command, shows output in a more verbose format.
--xml-interface¶When used with the introspect call, dump the XML description received from
the D-Bus org.freedesktop.DBus.Introspectable.Introspect call instead of the
normal output.
--json=MODE¶When used with the call or get-property command, shows output
formatted as JSON. Expects one of "short" (for the shortest possible output without any
redundant whitespace or line breaks) or "pretty" (for a pretty version of the same, with
indentation and line breaks). Note that transformation from D-Bus marshalling to JSON is done in a loss-less
way, which means type information is embedded into the JSON object tree.
-j¶Equivalent to --json=pretty when invoked interactively from a terminal. Otherwise
equivalent to --json=short, in particular when the output is piped to some other
program.
--expect-reply=BOOL¶When used with the call command,
specifies whether busctl shall wait for
completion of the method call, output the returned method
response data, and return success or failure via the process
exit code. If this is set to "no", the
method call will be issued but no response is expected, the
tool terminates immediately, and thus no response can be
shown, and no success or failure is returned via the exit
code. To only suppress output of the reply message payload,
use --quiet above. Defaults to
"yes".
--auto-start=BOOL¶When used with the call or emit command, specifies
whether the method call should implicitly activate the
called service, should it not be running yet but is
configured to be auto-started. Defaults to
"yes".
When used with the call command,
specifies whether the services may enforce interactive
authorization while executing the operation, if the security
policy is configured for this. Defaults to
"yes".
--timeout=SECS¶When used with the call command, specifies the maximum time to wait for
method call completion. When used with the monitor command, since version v257,
specifies the maximum time to wait for messages before automatically exiting. If no time unit is
specified, assumes seconds. The usual other units are understood, too (ms, us, s, min, h, d, w,
month, y). Note that this timeout does not apply if --expect-reply=no is used,
when combined with the call command, as the tool does not wait for any reply
message then. When not specified or when set to 0, the default of "25s" is
assumed for the call command, and it is disabled for the
monitor command.
--limit-messages=NUMBER, -N NUMBER¶When used with the monitor command, if enabled will make
busctl exit when the specified number of messages have been received and
printed. This is useful in combination with --match=, to wait for the specified
number of occurrences of specific D-Bus messages.
--augment-creds=BOOL¶Controls whether credential data reported by
list or status shall
be augmented with data from
/proc/. When this is turned on, the data
shown is possibly inconsistent, as the data read from
/proc/ might be more recent than the rest of
the credential information. Defaults to "yes".
--watch-bind=BOOL¶Controls whether to wait for the specified AF_UNIX bus socket to appear in the
file system before connecting to it. Defaults to off. When enabled, the tool will watch the file system until
the socket is created and then connect to it.
--destination=SERVICE¶Takes a service name. When used with the emit command, a signal is emitted to the specified service.
--user¶Talk to the service manager of the calling user, rather than the service manager of the system.
--system¶Talk to the service manager of the system. This is the implied default.
-H, --host=¶Execute the operation remotely. Specify a hostname, or a
username and hostname separated by "@", to
connect to. The hostname may optionally be suffixed by a
port ssh is listening on, separated by ":", and then a
container name, separated by "/", which
connects directly to a specific container on the specified
host. This will use SSH to talk to the remote machine manager
instance. Container names may be enumerated with
machinectl -H
HOST. Put IPv6 addresses in brackets.
-M, --machine=¶Execute operation on a local container. Specify a container name to connect to, optionally
prefixed by a user name to connect as and a separating "@" character. If the special
string ".host" is used in place of the container name, a connection to the local
system is made (which is useful to connect to a specific user's user bus: "--user
--machine=lennart@.host"). If the "@" syntax is not used, the connection is
made as root user. If the "@" syntax is used either the left hand side or the right hand
side may be omitted (but not both) in which case the local user name and ".host" are
implied.
-C, --capsule=¶Execute operation on a capsule. Specify a capsule name to connect to. See capsule@.service(5) for details about capsules.
-l, --full¶Do not ellipsize the output in list command.
--no-pager¶Do not pipe output into a pager.
--no-legend¶Do not print the legend, i.e. column headers and the footer with hints.
-h, --help¶--version¶The call and
set-property commands take a signature string
followed by a list of parameters formatted as string (for details
on D-Bus signature strings, see the Type
system chapter of the D-Bus specification). For simple
types, each parameter following the signature should simply be the
parameter's value formatted as string. Positive boolean values may
be formatted as "true", "yes",
"on", or "1"; negative boolean
values may be specified as "false",
"no", "off", or
"0". For arrays, a numeric argument for the
number of entries followed by the entries shall be specified. For
variants, the signature of the contents shall be specified,
followed by the contents. For dictionaries and structs, the
contents of them shall be directly specified.
For example,
s jawoll
is the formatting
of a single string "jawoll".
as 3 hello world foobar
is the formatting of a string array with three entries,
"hello", "world" and
"foobar".
a{sv} 3 One s Eins Two u 2 Yes b true
is the formatting of a dictionary
array that maps strings to variants, consisting of three
entries. The string "One" is assigned the
string "Eins". The string
"Two" is assigned the 32-bit unsigned
integer 2. The string "Yes" is assigned a
positive boolean.
Note that the call,
get-property, introspect
commands will also generate output in this format for the returned
data. Since this format is sometimes too terse to be easily
understood, the call and
get-property commands may generate a more
verbose, multi-line output when passed the
--verbose option.
Example 1. Write and Read a Property
The following two commands first write a property and then
read it back. The property is found on the
"/org/freedesktop/systemd1" object of the
"org.freedesktop.systemd1" service. The name of
the property is "LogLevel" on the
"org.freedesktop.systemd1.Manager"
interface. The property contains a single string:
# busctl set-property org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager LogLevel s debug # busctl get-property org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager LogLevel s "debug"
Example 2. Terse and Verbose Output
The following two commands read a property that contains an array of strings, and first show it in terse format, followed by verbose format:
$ busctl get-property org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager Environment
as 2 "LANG=en_US.UTF-8" "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin"
$ busctl get-property --verbose org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager Environment
ARRAY "s" {
STRING "LANG=en_US.UTF-8";
STRING "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin";
};Example 3. Invoking a Method
The following command invokes the
"StartUnit" method on the
"org.freedesktop.systemd1.Manager"
interface of the
"/org/freedesktop/systemd1" object
of the "org.freedesktop.systemd1"
service, and passes it two strings
"cups.service" and
"replace". As a result of the method
call, a single object path parameter is received and
shown:
# busctl call org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager StartUnit ss "cups.service" "replace" o "/org/freedesktop/systemd1/job/42684"