осмотрите автобус (Introspect the bus)
Имя (Name)
busctl - Introspect the bus
Синопсис (Synopsis)
busctl [OPTIONS...] [COMMAND] [NAME...]
Описание (Description)
busctl may be used to introspect and monitor the D-Bus bus.
Команды (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 pcap format (for
details, see the Libpcap File Formatwireshark(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.
Параметры (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
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".
--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.
PARAMETER FORMATTING
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 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.
Примеры (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"
Смотри также (See also)
dbus-daemon(1), D-Buswireshark(1)
Примечание (Note)
1. Libpcap File Format
https://wiki.wireshark.org/Development/LibpcapFileFormat
2. Type system chapter of the D-Bus specification
http://dbus.freedesktop.org/doc/dbus-specification.html#type-system
3. D-Bus
https://www.freedesktop.org/wiki/Software/dbus
