BUSCTL(1)                                                      busctl                                                     BUSCTL(1)

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
           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[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.

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"

SEE ALSO
       dbus-daemon(1), D-Bus[3], sd-bus(3), systemd(1), machinectl(1), wireshark(1)

NOTES
        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

systemd 252                                                                                                               BUSCTL(1)