NAME¶
busctl - Introspect the bus
SYNOPSIS¶
busctl [OPTIONS...] [COMMAND] [NAME...]
DESCRIPTION¶
busctl may be used to introspect and monitor the D-Bus
bus.
COMMANDS¶
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.
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).
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.
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.
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.
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.
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.
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.
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.
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.
help
Show command syntax help.
OPTIONS¶
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
--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".
--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".
--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.
--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.
-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
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,
is the formatting of a single string "jawoll".
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.
EXAMPLES¶
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"
NOTES¶
- 1.
- PCAP Next Generation (pcapng) Capture File Format
- 2.
- Type system chapter of the D-Bus specification
- 3.
- D-Bus