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NAME | SYNOPSIS | DESCRIPTION | COMMANDS | OPTIONS | PARAMETER FORMATTING | EXAMPLES | SEE ALSO | NOTES | COLOPHON |
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BUSCTL(1) busctl BUSCTL(1)
busctl - Introspect the bus
busctl [OPTIONS...] [COMMAND] [NAME...]
busctl may be used to introspect and monitor the D-Bus bus.
The following commands are understood:
list
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.
Added in version 209.
status [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).
Added in version 209.
monitor [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.
Added in version 209.
capture [SERVICE...]
Similar to monitor but writes the output in pcapng format
(for details, see PCAP Next Generation (pcapng) Capture File
Format[1]). 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.
Added in version 218.
tree [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.
Added in version 218.
introspect 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.
Added in version 218.
call 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.
Added in version 218.
emit 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.
Added in version 242.
get-property 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.
Added in version 218.
set-property 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.
Added in version 218.
help
Show command syntax help.
Added in version 209.
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).
Added in version 209.
--show-machine
When showing the list of peers, show a column containing the
names of containers they belong to. See
systemd-machined.service(8).
Added in version 209.
--unique
When showing the list of peers, show only "unique" names (of
the form ":number.number").
Added in version 209.
--acquired
The opposite of --unique — only "well-known" names will be
shown.
Added in version 209.
--activatable
When showing the list of peers, show only peers which have
actually not been activated yet, but may be started
automatically if accessed.
Added in version 209.
--match=MATCH
When showing messages being exchanged, show only the subset
matching MATCH. See sd_bus_add_match(3).
Added in version 209.
--size=
When used with the capture command, specifies the maximum bus
message size to capture ("snaplen"). Defaults to 4096 bytes.
Added in version 218.
--list
When used with the tree command, shows a flat list of object
paths instead of a tree.
Added in version 218.
-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.
Added in version 218.
--verbose
When used with the call or get-property command, shows output
in a more verbose format.
Added in version 218.
--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.
Added in version 243.
--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.
Added in version 240.
-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.
Added in version 240.
--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".
Added in version 218.
--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".
Added in version 218.
--allow-interactive-authorization=BOOL
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".
Added in version 218.
--timeout=SECS
When used with the call command, specifies the maximum time
to wait for method call completion. 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, 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.
Added in version 218.
--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".
Added in version 218.
--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.
Added in version 237.
--destination=SERVICE
Takes a service name. When used with the emit command, a
signal is emitted to the specified service.
Added in version 242.
--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
[email protected]"). 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 [email protected](5) for details about
capsules.
Added in version 256.
-l, --full
Do not ellipsize the output in list command.
Added in version 245.
--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
Print a short help text and exit.
--version
Print a short version string and exit.
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[2]). 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"
dbus-daemon(1), D-Bus[3], sd-bus(3), varlinkctl(1), systemd(1),
machinectl(1), wireshark(1)
1. PCAP Next Generation (pcapng) Capture File Format
https://github.com/pcapng/pcapng/
2. Type system chapter of the D-Bus specification
https://dbus.freedesktop.org/doc/dbus-specification.html#type-system
3. D-Bus
https://www.freedesktop.org/wiki/Software/dbus
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have
a bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-13.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
systemd 257~devel BUSCTL(1)
Pages that refer to this page: varlinkctl(1), sd-bus(3), sd_bus_add_node_enumerator(3), sd_bus_add_object(3), sd_bus_add_object_manager(3), sd_bus_emit_signal(3), [email protected](5), systemd.directives(7), systemd.index(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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