busctl(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | COMMANDS | OPTIONS | PARAMETER FORMATTING | EXAMPLES | SEE ALSO | NOTES | COLOPHON

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:

       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         top

       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         top

       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),
       wireshark(1)

NOTES         top

        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

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
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2020-06-09.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-06-09.)  If you discover any rendering 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 corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to man-pages@man7.org

systemd 245                                                        BUSCTL(1)

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