busctl(1) — Linux manual page


BUSCTL(1)                        busctl                        BUSCTL(1)

NAME         top

       busctl - Introspect the bus

SYNOPSIS         top

       busctl [OPTIONS...] [COMMAND] [NAME...]

DESCRIPTION         top

       busctl may be used to introspect and monitor the D-Bus bus.

COMMANDS         top

       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.

       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.

           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 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.

           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 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

           Show command syntax help.

OPTIONS         top

       The following options are understood:

           Connect to the bus specified by ADDRESS instead of using
           suitable defaults for either the system or user bus (see
           --system and --user options).

           When showing the list of peers, show a column containing the
           names of containers they belong to. See

           When showing the list of peers, show only "unique" names (of
           the form ":number.number").

           The opposite of --unique — only "well-known" names will be

           When showing the list of peers, show only peers which have
           actually not been activated yet, but may be started
           automatically if accessed.

           When showing messages being exchanged, show only the subset
           matching MATCH. See sd_bus_add_match(3).

           When used with the capture command, specifies the maximum bus
           message size to capture ("snaplen"). Defaults to 4096 bytes.

           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.

           When used with the call or get-property command, shows output
           in a more verbose format.

           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.

           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.

           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.

           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".

           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".

           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

           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".

           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.

           Takes a service name. When used with the emit command, a
           signal is emitted to the specified service.

           Talk to the service manager of the calling user, rather than
           the service manager of the 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

       -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.

           Do not pipe output into a pager.

           Do not print the legend, i.e. column headers and the footer
           with hints.

       -h, --help
           Print a short help text and exit.

           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.

EXAMPLES         top

       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         top

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

NOTES         top

        1. PCAP Next Generation (pcapng) Capture File Format

        2. Type system chapter of the D-Bus specification

        3. D-Bus

COLOPHON         top

       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
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2023-06-23.  (At that
       time, the date of the most recent commit that was found in the
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       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
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       (which is not part of the original manual page), send a mail to

systemd 253                                                    BUSCTL(1)

Pages that refer to this page: 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)systemd.directives(7)systemd.index(7)