man/busctl.xml

   1 <?xml version='1.0'?>
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7 -->
   8
   9 <refentry id="busctl"
  10           xmlns:xi="http://www.w3.org/2001/XInclude">
  11
  12   <refentryinfo>
  13     <title>busctl</title>
  14     <productname>systemd</productname>
  15   </refentryinfo>
  16
  17   <refmeta>
  18     <refentrytitle>busctl</refentrytitle>
  19     <manvolnum>1</manvolnum>
  20   </refmeta>
  21
  22   <refnamediv>
  23     <refname>busctl</refname>
  24     <refpurpose>Introspect the bus</refpurpose>
  25   </refnamediv>
  26
  27   <refsynopsisdiv>
  28     <cmdsynopsis>
  29       <command>busctl</command>
  30       <arg choice="opt" rep="repeat">OPTIONS</arg>
  31       <arg choice="opt">COMMAND</arg>
  32       <arg choice="opt" rep="repeat"><replaceable>NAME</replaceable></arg>
  33     </cmdsynopsis>
  34   </refsynopsisdiv>
  35
  36   <refsect1>
  37     <title>Description</title>
  38
  39     <para><command>busctl</command> may be used to
  40     introspect and monitor the D-Bus bus.</para>
  41   </refsect1>
  42
  43   <refsect1>
  44     <title>Options</title>
  45
  46     <para>The following options are understood:</para>
  47
  48     <variablelist>
  49       <varlistentry>
  50           <term><option>--address=<replaceable>ADDRESS</replaceable></option></term>
  51
  52           <listitem><para>Connect to the bus specified by
  53           <replaceable>ADDRESS</replaceable> instead of using suitable
  54           defaults for either the system or user bus (see
  55           <option>--system</option> and <option>--user</option>
  56           options).</para></listitem>
  57       </varlistentry>
  58
  59       <varlistentry>
  60           <term><option>--show-machine</option></term>
  61
  62           <listitem><para>When showing the list of peers, show a
  63           column containing the names of containers they belong to.
  64           See
  65           <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  66           </para></listitem>
  67       </varlistentry>
  68
  69       <varlistentry>
  70           <term><option>--unique</option></term>
  71
  72           <listitem><para>When showing the list of peers, show only
  73           "unique" names (of the form
  74           <literal>:<replaceable>number</replaceable>.<replaceable>number</replaceable></literal>).
  75           </para></listitem>
  76       </varlistentry>
  77
  78       <varlistentry>
  79           <term><option>--acquired</option></term>
  80
  81           <listitem><para>The opposite of <option>--unique</option> —
  82           only "well-known" names will be shown.</para></listitem>
  83       </varlistentry>
  84
  85       <varlistentry>
  86           <term><option>--activatable</option></term>
  87
  88           <listitem><para>When showing the list of peers, show only
  89           peers which have actually not been activated yet, but may be
  90           started automatically if accessed.</para>
  91           </listitem>
  92       </varlistentry>
  93
  94       <varlistentry>
  95           <term><option>--match=<replaceable>MATCH</replaceable></option></term>
  96
  97           <listitem><para>When showing messages being exchanged, show only the
  98           subset matching <replaceable>MATCH</replaceable>.
  99           See
 100           <citerefentry><refentrytitle>sd_bus_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 101           </para></listitem>
 102       </varlistentry>
 103
 104       <varlistentry>
 105         <term><option>--size=</option></term>
 106
 107         <listitem>
 108           <para>When used with the <command>capture</command> command,
 109           specifies the maximum bus message size to capture
 110           ("snaplen"). Defaults to 4096 bytes.</para>
 111         </listitem>
 112       </varlistentry>
 113
 114       <varlistentry>
 115         <term><option>--list</option></term>
 116
 117         <listitem>
 118           <para>When used with the <command>tree</command> command, shows a
 119           flat list of object paths instead of a tree.</para>
 120         </listitem>
 121       </varlistentry>
 122
 123       <varlistentry>
 124         <term><option>-q</option></term>
 125         <term><option>--quiet</option></term>
 126
 127         <listitem>
 128           <para>When used with the <command>call</command> command,
 129           suppresses display of the response message payload. Note that even
 130           if this option is specified, errors returned will still be
 131           printed and the tool will indicate success or failure with
 132           the process exit code.</para>
 133         </listitem>
 134       </varlistentry>
 135
 136       <varlistentry>
 137         <term><option>--verbose</option></term>
 138
 139         <listitem>
 140           <para>When used with the <command>call</command> or
 141           <command>get-property</command> command, shows output in a
 142           more verbose format.</para>
 143         </listitem>
 144       </varlistentry>
 145
 146       <varlistentry>
 147         <term><option>--json=</option><replaceable>MODE</replaceable></term>
 148
 149         <listitem>
 150           <para>When used with the <command>call</command> or <command>get-property</command> command, shows output
 151           formatted as JSON. Expects one of <literal>short</literal> (for the shortest possible output without any
 152           redundant whitespace or line breaks) or <literal>pretty</literal> (for a pretty version of the same, with
 153           indentation and line breaks). Note that transformation from D-Bus marshalling to JSON is done in a loss-less
 154           way, which means type information is embedded into the JSON object tree.</para>
 155         </listitem>
 156       </varlistentry>
 157
 158       <varlistentry>
 159         <term><option>-j</option></term>
 160
 161         <listitem>
 162           <para>Equivalent to <option>--json=pretty</option> when invoked interactively from a terminal. Otherwise
 163           equivalent to <option>--json=short</option>, in particular when the output is piped to some other
 164           program.</para>
 165         </listitem>
 166       </varlistentry>
 167
 168       <varlistentry>
 169         <term><option>--expect-reply=</option><replaceable>BOOL</replaceable></term>
 170
 171         <listitem>
 172           <para>When used with the <command>call</command> command,
 173           specifies whether <command>busctl</command> shall wait for
 174           completion of the method call, output the returned method
 175           response data, and return success or failure via the process
 176           exit code. If this is set to <literal>no</literal>, the
 177           method call will be issued but no response is expected, the
 178           tool terminates immediately, and thus no response can be
 179           shown, and no success or failure is returned via the exit
 180           code. To only suppress output of the reply message payload,
 181           use <option>--quiet</option> above. Defaults to
 182           <literal>yes</literal>.</para>
 183         </listitem>
 184       </varlistentry>
 185
 186       <varlistentry>
 187         <term><option>--auto-start=</option><replaceable>BOOL</replaceable></term>
 188
 189         <listitem>
 190           <para>When used with the <command>call</command> or <command>emit</command> command, specifies
 191           whether the method call should implicitly activate the
 192           called service, should it not be running yet but is
 193           configured to be auto-started. Defaults to
 194           <literal>yes</literal>.</para>
 195         </listitem>
 196       </varlistentry>
 197
 198       <varlistentry>
 199         <term><option>--allow-interactive-authorization=</option><replaceable>BOOL</replaceable></term>
 200
 201         <listitem>
 202           <para>When used with the <command>call</command> command,
 203           specifies whether the services may enforce interactive
 204           authorization while executing the operation, if the security
 205           policy is configured for this. Defaults to
 206           <literal>yes</literal>.</para>
 207         </listitem>
 208       </varlistentry>
 209
 210       <varlistentry>
 211         <term><option>--timeout=</option><replaceable>SECS</replaceable></term>
 212
 213         <listitem>
 214           <para>When used with the <command>call</command> command,
 215           specifies the maximum time to wait for method call
 216           completion. If no time unit is specified, assumes
 217           seconds. The usual other units are understood, too (ms, us,
 218           s, min, h, d, w, month, y). Note that this timeout does not
 219           apply if <option>--expect-reply=no</option> is used, as the
 220           tool does not wait for any reply message then. When not
 221           specified or when set to 0, the default of
 222           <literal>25s</literal> is assumed.</para>
 223         </listitem>
 224       </varlistentry>
 225
 226       <varlistentry>
 227         <term><option>--augment-creds=</option><replaceable>BOOL</replaceable></term>
 228
 229         <listitem>
 230           <para>Controls whether credential data reported by
 231           <command>list</command> or <command>status</command> shall
 232           be augmented with data from
 233           <filename>/proc</filename>. When this is turned on, the data
 234           shown is possibly inconsistent, as the data read from
 235           <filename>/proc</filename> might be more recent than the rest of
 236           the credential information. Defaults to <literal>yes</literal>.</para>
 237         </listitem>
 238       </varlistentry>
 239
 240       <varlistentry>
 241         <term><option>--watch-bind=</option><replaceable>BOOL</replaceable></term>
 242
 243         <listitem>
 244           <para>Controls whether to wait for the specified <constant>AF_UNIX</constant> bus socket to appear in the
 245           file system before connecting to it. Defaults to off. When enabled, the tool will watch the file system until
 246           the socket is created and then connect to it.</para>
 247         </listitem>
 248       </varlistentry>
 249
 250       <varlistentry>
 251         <term><option>--destination=</option><replaceable>SERVICE</replaceable></term>
 252
 253         <listitem>
 254           <para>Takes a service name. When used with the <command>emit</command> command, a signal is
 255           emitted to the specified service.</para>
 256         </listitem>
 257       </varlistentry>
 258
 259       <xi:include href="user-system-options.xml" xpointer="user" />
 260       <xi:include href="user-system-options.xml" xpointer="system" />
 261       <xi:include href="user-system-options.xml" xpointer="host" />
 262       <xi:include href="user-system-options.xml" xpointer="machine" />
 263
 264       <xi:include href="standard-options.xml" xpointer="no-pager" />
 265       <xi:include href="standard-options.xml" xpointer="no-legend" />
 266       <xi:include href="standard-options.xml" xpointer="help" />
 267       <xi:include href="standard-options.xml" xpointer="version" />
 268     </variablelist>
 269   </refsect1>
 270
 271   <refsect1>
 272     <title>Commands</title>
 273
 274     <para>The following commands are understood:</para>
 275
 276     <variablelist>
 277       <varlistentry>
 278         <term><command>list</command></term>
 279
 280         <listitem><para>Show all peers on the bus, by their service
 281         names. By default, shows both unique and well-known names, but
 282         this may be changed with the <option>--unique</option> and
 283         <option>--acquired</option> switches. This is the default
 284         operation if no command is specified.</para></listitem>
 285       </varlistentry>
 286
 287       <varlistentry>
 288         <term><command>status</command> <arg choice="opt"><replaceable>SERVICE</replaceable></arg></term>
 289
 290         <listitem><para>Show process information and credentials of a
 291         bus service (if one is specified by its unique or well-known
 292         name), a process (if one is specified by its numeric PID), or
 293         the owner of the bus (if no parameter is
 294         specified).</para></listitem>
 295       </varlistentry>
 296
 297       <varlistentry>
 298         <term><command>monitor</command> <arg choice="opt" rep="repeat"><replaceable>SERVICE</replaceable></arg></term>
 299
 300         <listitem><para>Dump messages being exchanged. If
 301         <replaceable>SERVICE</replaceable> is specified, show messages
 302         to or from this peer, identified by its well-known or unique
 303         name. Otherwise, show all messages on the bus. Use
 304         <keycombo><keycap>Ctrl</keycap><keycap>C</keycap></keycombo>
 305         to terminate the dump.</para></listitem>
 306       </varlistentry>
 307
 308       <varlistentry>
 309         <term><command>capture</command> <arg choice="opt" rep="repeat"><replaceable>SERVICE</replaceable></arg></term>
 310
 311         <listitem><para>Similar to <command>monitor</command> but
 312         writes the output in pcap format (for details, see the <ulink
 313         url="https://wiki.wireshark.org/Development/LibpcapFileFormat">Libpcap
 314         File Format</ulink> description). Make sure to redirect
 315         standard output to a file. Tools like
 316         <citerefentry project='die-net'><refentrytitle>wireshark</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 317         may be used to dissect and view the resulting
 318         files.</para></listitem>
 319       </varlistentry>
 320
 321       <varlistentry>
 322         <term><command>tree</command> <arg choice="opt" rep="repeat"><replaceable>SERVICE</replaceable></arg></term>
 323
 324         <listitem><para>Shows an object tree of one or more
 325         services. If <replaceable>SERVICE</replaceable> is specified,
 326         show object tree of the specified services only. Otherwise,
 327         show all object trees of all services on the bus that acquired
 328         at least one well-known name.</para></listitem>
 329       </varlistentry>
 330
 331       <varlistentry>
 332         <term><command>introspect</command> <arg choice="plain"><replaceable>SERVICE</replaceable></arg> <arg choice="plain"><replaceable>OBJECT</replaceable></arg> <arg choice="opt"><replaceable>INTERFACE</replaceable></arg></term>
 333
 334         <listitem><para>Show interfaces, methods, properties and
 335         signals of the specified object (identified by its path) on
 336         the specified service. If the interface argument is passed, the
 337         output is limited to members of the specified
 338         interface.</para></listitem>
 339       </varlistentry>
 340
 341       <varlistentry>
 342         <term><command>call</command> <arg choice="plain"><replaceable>SERVICE</replaceable></arg> <arg choice="plain"><replaceable>OBJECT</replaceable></arg> <arg choice="plain"><replaceable>INTERFACE</replaceable></arg> <arg choice="plain"><replaceable>METHOD</replaceable></arg> <arg choice="opt"><replaceable>SIGNATURE</replaceable> <arg choice="opt" rep="repeat"><replaceable>ARGUMENT</replaceable></arg></arg></term>
 343
 344         <listitem><para>Invoke a method and show the response. Takes a
 345         service name, object path, interface name and method name. If
 346         parameters shall be passed to the method call, a signature
 347         string is required, followed by the arguments, individually
 348         formatted as strings. For details on the formatting used, see
 349         below. To suppress output of the returned data, use the
 350         <option>--quiet</option> option.</para></listitem>
 351       </varlistentry>
 352
 353       <varlistentry>
 354         <term><command>emit</command> <arg choice="plain"><replaceable>OBJECT</replaceable></arg> <arg choice="plain"><replaceable>INTERFACE</replaceable></arg> <arg choice="plain"><replaceable>SIGNAL</replaceable></arg> <arg choice="opt"><replaceable>SIGNATURE</replaceable> <arg choice="opt" rep="repeat"><replaceable>ARGUMENT</replaceable></arg></arg></term>
 355
 356         <listitem><para>Emit a signal. Takes a object path, interface name and method name. If parameters
 357         shall be passed, a signature string is required, followed by the arguments, individually formatted as
 358         strings. For details on the formatting used, see below. To specify the destination of the signal,
 359         use the <option>--destination=</option> option.</para></listitem>
 360       </varlistentry>
 361
 362       <varlistentry>
 363         <term><command>get-property</command> <arg choice="plain"><replaceable>SERVICE</replaceable></arg> <arg choice="plain"><replaceable>OBJECT</replaceable></arg> <arg choice="plain"><replaceable>INTERFACE</replaceable></arg> <arg choice="plain" rep="repeat"><replaceable>PROPERTY</replaceable></arg></term>
 364
 365         <listitem><para>Retrieve the current value of one or more
 366         object properties. Takes a service name, object path,
 367         interface name and property name. Multiple properties may be
 368         specified at once, in which case their values will be shown one
 369         after the other, separated by newlines. The output is, by
 370         default, in terse format. Use <option>--verbose</option> for a
 371         more elaborate output format.</para></listitem>
 372       </varlistentry>
 373
 374       <varlistentry>
 375         <term><command>set-property</command> <arg choice="plain"><replaceable>SERVICE</replaceable></arg> <arg choice="plain"><replaceable>OBJECT</replaceable></arg> <arg choice="plain"><replaceable>INTERFACE</replaceable></arg> <arg choice="plain"><replaceable>PROPERTY</replaceable></arg> <arg choice="plain"><replaceable>SIGNATURE</replaceable></arg> <arg choice="plain" rep="repeat"><replaceable>ARGUMENT</replaceable></arg></term>
 376
 377         <listitem><para>Set the current value of an object
 378         property. Takes a service name, object path, interface name,
 379         property name, property signature, followed by a list of
 380         parameters formatted as strings.</para></listitem>
 381       </varlistentry>
 382
 383       <varlistentry>
 384         <term><command>help</command></term>
 385
 386         <listitem><para>Show command syntax help.</para></listitem>
 387       </varlistentry>
 388     </variablelist>
 389   </refsect1>
 390
 391   <refsect1>
 392     <title>Parameter Formatting</title>
 393
 394     <para>The <command>call</command> and
 395     <command>set-property</command> commands take a signature string
 396     followed by a list of parameters formatted as string (for details
 397     on D-Bus signature strings, see the <ulink
 398     url="http://dbus.freedesktop.org/doc/dbus-specification.html#type-system">Type
 399     system chapter of the D-Bus specification</ulink>). For simple
 400     types, each parameter following the signature should simply be the
 401     parameter's value formatted as string. Positive boolean values may
 402     be formatted as <literal>true</literal>, <literal>yes</literal>,
 403     <literal>on</literal>, or <literal>1</literal>; negative boolean
 404     values may be specified as <literal>false</literal>,
 405     <literal>no</literal>, <literal>off</literal>, or
 406     <literal>0</literal>. For arrays, a numeric argument for the
 407     number of entries followed by the entries shall be specified. For
 408     variants, the signature of the contents shall be specified,
 409     followed by the contents. For dictionaries and structs, the
 410     contents of them shall be directly specified.</para>
 411
 412     <para>For example,
 413     <programlisting>s jawoll</programlisting> is the formatting
 414     of a single string <literal>jawoll</literal>.</para>
 415
 416     <para>
 417     <programlisting>as 3 hello world foobar</programlisting>
 418     is the formatting of a string array with three entries,
 419     <literal>hello</literal>, <literal>world</literal> and
 420     <literal>foobar</literal>.</para>
 421
 422     <para>
 423     <programlisting>a{sv} 3 One s Eins Two u 2 Yes b true</programlisting>
 424     is the formatting of a dictionary
 425     array that maps strings to variants, consisting of three
 426     entries. The string <literal>One</literal> is assigned the
 427     string <literal>Eins</literal>. The string
 428     <literal>Two</literal> is assigned the 32-bit unsigned
 429     integer 2. The string <literal>Yes</literal> is assigned a
 430     positive boolean.</para>
 431
 432     <para>Note that the <command>call</command>,
 433     <command>get-property</command>, <command>introspect</command>
 434     commands will also generate output in this format for the returned
 435     data. Since this format is sometimes too terse to be easily
 436     understood, the <command>call</command> and
 437     <command>get-property</command> commands may generate a more
 438     verbose, multi-line output when passed the
 439     <option>--verbose</option> option.</para>
 440   </refsect1>
 441
 442   <refsect1>
 443     <title>Examples</title>
 444
 445     <example>
 446       <title>Write and Read a Property</title>
 447
 448       <para>The following two commands first write a property and then
 449       read it back. The property is found on the
 450       <literal>/org/freedesktop/systemd1</literal> object of the
 451       <literal>org.freedesktop.systemd1</literal> service. The name of
 452       the property is <literal>LogLevel</literal> on the
 453       <literal>org.freedesktop.systemd1.Manager</literal>
 454       interface. The property contains a single string:</para>
 455
 456       <programlisting># busctl set-property org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager LogLevel s debug
 457 # busctl get-property org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager LogLevel
 458 s "debug"</programlisting>
 459
 460     </example>
 461
 462     <example>
 463       <title>Terse and Verbose Output</title>
 464
 465       <para>The following two commands read a property that contains
 466       an array of strings, and first show it in terse format, followed
 467       by verbose format:</para>
 468
 469       <programlisting>$ busctl get-property org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager Environment
 470 as 2 "LANG=en_US.UTF-8" "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin"
 471 $ busctl get-property --verbose org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager Environment
 472 ARRAY "s" {
 473         STRING "LANG=en_US.UTF-8";
 474         STRING "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin";
 475 };</programlisting>
 476     </example>
 477
 478     <example>
 479       <title>Invoking a Method</title>
 480
 481       <para>The following command invokes the
 482       <literal>StartUnit</literal> method on the
 483       <literal>org.freedesktop.systemd1.Manager</literal>
 484       interface of the
 485       <literal>/org/freedesktop/systemd1</literal> object
 486       of the <literal>org.freedesktop.systemd1</literal>
 487       service, and passes it two strings
 488       <literal>cups.service</literal> and
 489       <literal>replace</literal>. As a result of the method
 490       call, a single object path parameter is received and
 491       shown:</para>
 492
 493       <programlisting># busctl call org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager StartUnit ss "cups.service" "replace"
 494 o "/org/freedesktop/systemd1/job/42684"</programlisting>
 495     </example>
 496   </refsect1>
 497
 498   <refsect1>
 499     <title>See Also</title>
 500
 501     <para>
 502       <citerefentry project='dbus'><refentrytitle>dbus-daemon</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 503       <ulink url="https://www.freedesktop.org/wiki/Software/dbus">D-Bus</ulink>,
 504       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 505       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 506       <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 507       <citerefentry project='die-net'><refentrytitle>wireshark</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 508     </para>
 509   </refsect1>
 510 </refentry>