busctl

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 pcap format (for
           details, see the Libpcap File Format[1] description). Make sure to
           redirect standard output to a file. 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 a 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.

       -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. 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

systemd 245                                                          BUSCTL(1)