1 IPC interface (interprocess communication)
2 ==========================================
3 Michael Stapelberg <michael@i3wm.org>
6 This document describes how to interface with i3 from a separate process. This
7 is useful for example to remote-control i3 (to write test cases for example) or
8 to get various information like the current workspaces to implement an external
11 The method of choice for IPC in our case is a unix socket because it has very
12 little overhead on both sides and is usually available without headaches in
13 most languages. In the default configuration file, the ipc-socket gets created
14 in +/tmp/i3-%u.XXXXXX/ipc-socket.%p+ where +%u+ is your UNIX username, +%p+ is
15 the PID of i3 and XXXXXX is a string of random characters from the portable
16 filename character set (see mkdtemp(3)). You can get the socketpath from i3 by
17 calling +i3 --get-socketpath+.
19 All i3 utilities, like +i3-msg+ and +i3-input+ will read the +I3_SOCKET_PATH+
20 X11 property, stored on the X11 root window.
23 .Use an existing library!
24 There are existing libraries for many languages. You can have a look at
25 <<libraries>> or search the web if your language of choice is not mentioned.
26 Usually, it is not necessary to implement low-level communication with i3
29 == Establishing a connection
31 To establish a connection, simply open the IPC socket. The following code
32 snippet illustrates this in Perl:
34 -------------------------------------------------------------
36 chomp(my $path = qx(i3 --get-socketpath));
37 my $sock = IO::Socket::UNIX->new(Peer => $path);
38 -------------------------------------------------------------
40 == Sending messages to i3
42 To send a message to i3, you have to format in the binary message format which
43 i3 expects. This format specifies a magic string in the beginning to ensure
44 the integrity of messages (to prevent follow-up errors). Following the magic
45 string comes the length of the payload of the message as 32-bit integer, and
46 the type of the message as 32-bit integer (the integers are not converted, so
47 they are in native byte order).
49 The magic string currently is "i3-ipc" and will only be changed when a change
50 in the IPC API is done which breaks compatibility (we hope that we don’t need
53 .Currently implemented message types
54 [options="header",cols="^10%,^20%,^20%,^50%"]
55 |======================================================
56 | Type (numeric) | Type (name) | Reply type | Purpose
57 | 0 | +RUN_COMMAND+ | <<_command_reply,COMMAND>> | Run the payload as an i3 command (like the commands you can bind to keys).
58 | 1 | +GET_WORKSPACES+ | <<_workspaces_reply,WORKSPACES>> | Get the list of current workspaces.
59 | 2 | +SUBSCRIBE+ | <<_subscribe_reply,SUBSCRIBE>> | Subscribe this IPC connection to the event types specified in the message payload. See <<events>>.
60 | 3 | +GET_OUTPUTS+ | <<_outputs_reply,OUTPUTS>> | Get the list of current outputs.
61 | 4 | +GET_TREE+ | <<_tree_reply,TREE>> | Get the i3 layout tree.
62 | 5 | +GET_MARKS+ | <<_marks_reply,MARKS>> | Gets the names of all currently set marks.
63 | 6 | +GET_BAR_CONFIG+ | <<_bar_config_reply,BAR_CONFIG>> | Gets the specified bar configuration or the names of all bar configurations if payload is empty.
64 | 7 | +GET_VERSION+ | <<_version_reply,VERSION>> | Gets the i3 version.
65 | 8 | +GET_BINDING_MODES+ | <<_binding_modes_reply,BINDING_MODES>> | Gets the names of all currently configured binding modes.
66 |======================================================
68 So, a typical message could look like this:
69 --------------------------------------------------
70 "i3-ipc" <message length> <message type> <payload>
71 --------------------------------------------------
74 ------------------------------------------------------------------------------
75 00000000 69 33 2d 69 70 63 04 00 00 00 00 00 00 00 65 78 |i3-ipc........ex|
77 ------------------------------------------------------------------------------
79 To generate and send such a message, you could use the following code in Perl:
80 ------------------------------------------------------------
81 sub format_ipc_command {
84 # Get the real byte count (vs. amount of characters)
85 { use bytes; $len = length($msg); }
86 return "i3-ipc" . pack("LL", $len, 0) . $msg;
89 $sock->write(format_ipc_command("exit"));
90 ------------------------------------------------------------------------------
92 == Receiving replies from i3
94 Replies from i3 usually consist of a simple string (the length of the string
95 is the message_length, so you can consider them length-prefixed) which in turn
96 contain the JSON serialization of a data structure. For example, the
97 GET_WORKSPACES message returns an array of workspaces (each workspace is a map
98 with certain attributes).
102 The reply format is identical to the normal message format. There also is
103 the magic string, then the message length, then the message type and the
106 The following reply types are implemented:
109 Confirmation/Error code for the RUN_COMMAND message.
111 Reply to the GET_WORKSPACES message.
113 Confirmation/Error code for the SUBSCRIBE message.
115 Reply to the GET_OUTPUTS message.
117 Reply to the GET_TREE message.
119 Reply to the GET_MARKS message.
121 Reply to the GET_BAR_CONFIG message.
123 Reply to the GET_VERSION message.
125 Reply to the GET_BINDING_MODES message.
130 The reply consists of a list of serialized maps for each command that was
131 parsed. Each has the property +success (bool)+ and may also include a
132 human-readable error message in the property +error (string)+.
136 [{ "success": true }]
139 [[_workspaces_reply]]
142 The reply consists of a serialized list of workspaces. Each workspace has the
143 following properties:
146 The logical number of the workspace. Corresponds to the command
147 to switch to this workspace. For named workspaces, this will be -1.
149 The name of this workspace (by default num+1), as changed by the
150 user. Encoded in UTF-8.
152 Whether this workspace is currently visible on an output (multiple
153 workspaces can be visible at the same time).
155 Whether this workspace currently has the focus (only one workspace
156 can have the focus at the same time).
158 Whether a window on this workspace has the "urgent" flag set.
160 The rectangle of this workspace (equals the rect of the output it
161 is on), consists of x, y, width, height.
163 The video output this workspace is on (LVDS1, VGA1, …).
202 The reply consists of a single serialized map. The only property is
203 +success (bool)+, indicating whether the subscription was successful (the
204 default) or whether a JSON parse error occurred.
214 The reply consists of a serialized list of outputs. Each output has the
215 following properties:
218 The name of this output (as seen in +xrandr(1)+). Encoded in UTF-8.
220 Whether this output is currently active (has a valid mode).
222 Whether this output is currently the primary output.
223 current_workspace (string)::
224 The name of the current workspace that is visible on this output. +null+ if
225 the output is not active.
227 The rectangle of this output (equals the rect of the output it
228 is on), consists of x, y, width, height.
236 "current_workspace": "4",
247 "current_workspace": "1",
261 The reply consists of a serialized tree. Each node in the tree (representing
262 one container) has at least the properties listed below. While the nodes might
263 have more properties, please do not use any properties which are not documented
264 here. They are not yet finalized and will probably change!
267 The internal ID (actually a C pointer value) of this container. Do not
268 make any assumptions about it. You can use it to (re-)identify and
269 address containers when talking to i3.
271 The internal name of this container. For all containers which are part
272 of the tree structure down to the workspace contents, this is set to a
273 nice human-readable name of the container.
274 For containers that have an X11 window, the content is the title
275 (_NET_WM_NAME property) of that window.
276 For all other containers, the content is not defined (yet).
278 Type of this container. Can be one of "root", "output", "con",
279 "floating_con", "workspace" or "dockarea".
281 Can be either "normal", "none" or "pixel", depending on the
282 container’s border style.
283 current_border_width (integer)::
284 Number of pixels of the border width.
286 Can be either "splith", "splitv", "stacked", "tabbed", "dockarea" or
288 Other values might be possible in the future, should we add new
290 orientation (string)::
291 Can be either "none" (for non-split containers), "horizontal" or
293 THIS FIELD IS OBSOLETE. It is still present, but your code should not
294 use it. Instead, rely on the layout field.
296 The percentage which this container takes in its parent. A value of
297 +null+ means that the percent property does not make sense for this
298 container, for example for the root container.
300 The absolute display coordinates for this container. Display
301 coordinates means that when you have two 1600x1200 monitors on a single
302 X11 Display (the standard way), the coordinates of the first window on
303 the second monitor are +{ "x": 1600, "y": 0, "width": 1600, "height":
306 The coordinates of the *actual client window* inside its container.
307 These coordinates are relative to the container and do not include the
308 window decoration (which is actually rendered on the parent container).
309 So, when using the +default+ layout, you will have a 2 pixel border on
310 each side, making the window_rect +{ "x": 2, "y": 0, "width": 632,
311 "height": 366 }+ (for example).
313 The coordinates of the *window decoration* inside its container. These
314 coordinates are relative to the container and do not include the actual
317 The original geometry the window specified when i3 mapped it. Used when
318 switching a window to floating mode, for example.
320 The X11 window ID of the *actual client window* inside this container.
321 This field is set to null for split containers or otherwise empty
322 containers. This ID corresponds to what xwininfo(1) and other
323 X11-related tools display (usually in hex).
325 Whether this container (window, split container, floating container or
326 workspace) has the urgency hint set, directly or indirectly. All parent
327 containers up until the workspace container will be marked urgent if they
328 have at least one urgent child.
330 Whether this container is currently focused.
331 focus (array of integer)::
332 List of child node IDs (see +nodes+, +floating_nodes+ and +id+) in focus
333 order. Traversing the tree by following the first entry in this array
334 will result in eventually reaching the one node with +focused+ set to
336 nodes (array of node)::
337 The tiling (i.e. non-floating) child containers of this node.
338 floating_nodes (array of node)::
339 The floating child containers of this node. Only non-empty on nodes with
342 Please note that in the following example, I have left out some keys/values
343 which are not relevant for the type of the node. Otherwise, the example would
344 be by far too long (it already is quite long, despite showing only 1 window and
347 It is useful to have an overview of the structure before taking a look at the
361 -----------------------
388 "layout": "dockarea",
389 "orientation": "vertical",
412 "orientation": "horizontal",
419 "floating_nodes": [],
443 "name": "bottomdock",
444 "layout": "dockarea",
445 "orientation": "vertical",
472 ------------------------
477 The reply consists of a single array of strings for each container that has a
478 mark. A mark can only be set on one container, so the array is unique.
479 The order of that array is undefined.
481 If no window has a mark the response will be the empty array [].
483 [[_bar_config_reply]]
486 This can be used by third-party workspace bars (especially i3bar, but others
487 are free to implement compatible alternatives) to get the +bar+ block
488 configuration from i3.
490 Depending on the input, the reply is either:
493 An array of configured bar IDs
495 A JSON map containing the configuration for the specified bar.
497 Each bar configuration has the following properties:
500 The ID for this bar. Included in case you request multiple
501 configurations and want to differentiate the different replies.
503 Either +dock+ (the bar sets the dock window type) or +hide+ (the bar
504 does not show unless a specific key is pressed).
506 Either +bottom+ or +top+ at the moment.
507 status_command (string)::
508 Command which will be run to generate a statusline. Each line on stdout
509 of this command will be displayed in the bar. At the moment, no
510 formatting is supported.
512 The font to use for text on the bar.
513 workspace_buttons (boolean)::
514 Display workspace buttons or not? Defaults to true.
515 binding_mode_indicator (boolean)::
516 Display the mode indicator or not? Defaults to true.
518 Should the bar enable verbose output for debugging? Defaults to false.
520 Contains key/value pairs of colors. Each value is a color code in hex,
521 formatted #rrggbb (like in HTML).
523 The following colors can be configured at the moment:
526 Background color of the bar.
528 Text color to be used for the statusline.
530 Text color to be used for the separator.
532 Background color of the bar on the currently focused monitor output.
534 Text color to be used for the statusline on the currently focused
537 Text color to be used for the separator on the currently focused
539 focused_workspace_text/focused_workspace_bg/focused_workspace_border::
540 Text/background/border color for a workspace button when the workspace
542 active_workspace_text/active_workspace_bg/active_workspace_border::
543 Text/background/border color for a workspace button when the workspace
544 is active (visible) on some output, but the focus is on another one.
545 You can only tell this apart from the focused workspace when you are
546 using multiple monitors.
547 inactive_workspace_text/inactive_workspace_bg/inactive_workspace_border::
548 Text/background/border color for a workspace button when the workspace
549 does not have focus and is not active (visible) on any output. This
550 will be the case for most workspaces.
551 urgent_workspace_text/urgent_workspace_bg/urgent_workspace_border::
552 Text/background/border color for workspaces which contain at least one
553 window with the urgency hint set.
554 binding_mode_text/binding_mode_bg/binding_mode_border::
555 Text/background/border color for the binding mode indicator.
558 *Example of configured bars:*
563 *Example of bar configuration:*
568 "position": "bottom",
569 "status_command": "i3status",
570 "font": "-misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1",
571 "workspace_buttons": true,
572 "binding_mode_indicator": true,
575 "background": "#c0c0c0",
576 "statusline": "#00ff00",
577 "focused_workspace_text": "#ffffff",
578 "focused_workspace_bg": "#000000"
586 The reply consists of a single JSON dictionary with the following keys:
589 The major version of i3, such as +4+.
591 The minor version of i3, such as +2+. Changes in the IPC interface (new
592 features) will only occur with new minor (or major) releases. However,
593 bugfixes might be introduced in patch releases, too.
595 The patch version of i3, such as +1+ (when the complete version is
596 +4.2.1+). For versions such as +4.2+, patch will be set to +0+.
597 human_readable (string)::
598 A human-readable version of i3 containing the precise git version,
599 build date and branch name. When you need to display the i3 version to
600 your users, use the human-readable version whenever possible (since
601 this is what +i3 --version+ displays, too).
602 loaded_config_file_name (string)::
603 The current config path.
608 "human_readable" : "4.2-169-gf80b877 (2012-08-05, branch \"next\")",
609 "loaded_config_file_name" : "/home/hwangcc23/.i3/config",
616 [[_binding_modes_reply]]
617 === BINDING_MODES reply
619 The reply consists of an array of all currently configured binding modes.
622 ---------------------
623 ["default", "resize"]
624 ---------------------
630 To get informed when certain things happen in i3, clients can subscribe to
631 events. Events consist of a name (like "workspace") and an event reply type
632 (like I3_IPC_EVENT_WORKSPACE). The events sent by i3 are in the same format
633 as replies to specific commands. However, the highest bit of the message type
634 is set to 1 to indicate that this is an event reply instead of a normal reply.
636 Caveat: As soon as you subscribe to an event, it is not guaranteed any longer
637 that the requests to i3 are processed in order. This means, the following
638 situation can happen: You send a GET_WORKSPACES request but you receive a
639 "workspace" event before receiving the reply to GET_WORKSPACES. If your
640 program does not want to cope which such kinds of race conditions (an
641 event based library may not have a problem here), I suggest you create a
642 separate connection to receive events.
644 === Subscribing to events
646 By sending a message of type SUBSCRIBE with a JSON-encoded array as payload
647 you can register to an event.
650 ---------------------------------
652 payload: [ "workspace", "output" ]
653 ---------------------------------
658 The numbers in parenthesis is the event type (keep in mind that you need to
659 strip the highest bit first).
662 Sent when the user switches to a different workspace, when a new
663 workspace is initialized or when a workspace is removed (because the
664 last client vanished).
666 Sent when RandR issues a change notification (of either screens,
667 outputs, CRTCs or output properties).
669 Sent whenever i3 changes its binding mode.
671 Sent when a client's window is successfully reparented (that is when i3
672 has finished fitting it into a container), when a window received input
673 focus or when certain properties of the window have changed.
674 barconfig_update (4)::
675 Sent when the hidden_state or mode field in the barconfig of any bar
676 instance was updated and when the config is reloaded.
678 Sent when a configured command binding is triggered with the keyboard or
681 Sent when the ipc shuts down because of a restart or exit by user command
684 --------------------------------------------------------------------
685 # the appropriate 4 bytes read from the socket are stored in $input
687 # unpack a 32-bit unsigned integer
688 my $message_type = unpack("L", $input);
690 # check if the highest bit is 1
691 my $is_event = (($message_type >> 31) == 1);
694 my $event_type = ($message_type & 0x7F);
697 say "Received event of type $event_type";
699 --------------------------------------------------------------------
703 This event consists of a single serialized map containing a property
704 +change (string)+ which indicates the type of the change ("focus", "init",
705 "empty", "urgent", "reload", "rename", "restored", "move"). A
706 +current (object)+ property will be present with the affected workspace
707 whenever the type of event affects a workspace (otherwise, it will be +null).
709 When the change is "focus", an +old (object)+ property will be present with the
710 previous workspace. When the first switch occurs (when i3 focuses the
711 workspace visible at the beginning) there is no previous workspace, and the
712 +old+ property will be set to +null+. Also note that if the previous is empty
713 it will get destroyed when switching, but will still be present in the "old"
717 ---------------------
731 ---------------------
735 This event consists of a single serialized map containing a property
736 +change (string)+ which indicates the type of the change (currently only
740 ---------------------------
741 { "change": "unspecified" }
742 ---------------------------
746 This event consists of a single serialized map containing a property
747 +change (string)+ which holds the name of current mode in use. The name
748 is the same as specified in config when creating a mode. The default
749 mode is simply named default. It contains a second property, +pango_markup+, which
750 defines whether pango markup shall be used for displaying this mode.
753 ---------------------------
758 ---------------------------
762 This event consists of a single serialized map containing a property
763 +change (string)+ which indicates the type of the change
765 * +new+ – the window has become managed by i3
766 * +close+ – the window has closed
767 * +focus+ – the window has received input focus
768 * +title+ – the window's title has changed
769 * +fullscreen_mode+ – the window has entered or exited fullscreen mode
770 * +move+ – the window has changed its position in the tree
771 * +floating+ – the window has transitioned to or from floating
772 * +urgent+ – the window has become urgent or lost its urgent status
773 * +mark+ – a mark has been added to or removed from the window
775 Additionally a +container (object)+ field will be present, which consists
776 of the window's parent container. Be aware that for the "new" event, the
777 container will hold the initial name of the newly reparented window (e.g.
778 if you run urxvt with a shell that changes the title, you will still at
779 this point get the window title as "urxvt").
782 ---------------------------
791 ---------------------------
793 === barconfig_update event
795 This event consists of a single serialized map reporting on options from the
796 barconfig of the specified bar_id that were updated in i3. This event is the
797 same as a +GET_BAR_CONFIG+ reply for the bar with the given id.
801 This event consists of a single serialized map reporting on the details of a
802 binding that ran a command because of user input. The +change (string)+ field
803 indicates what sort of binding event was triggered (right now it will always be
804 +"run"+ but may be expanded in the future).
806 The +binding (object)+ field contains details about the binding that was run:
809 The i3 command that is configured to run for this binding.
810 event_state_mask (array of strings)::
811 The group and modifier keys that were configured with this binding.
812 input_code (integer)::
813 If the binding was configured with +bindcode+, this will be the key code
814 that was given for the binding. If the binding is a mouse binding, it will be
815 the number of the mouse button that was pressed. Otherwise it will be 0.
816 symbol (string or null)::
817 If this is a keyboard binding that was configured with +bindsym+, this
818 field will contain the given symbol. Otherwise it will be +null+.
819 input_type (string)::
820 This will be +"keyboard"+ or +"mouse"+ depending on whether or not this was
821 a keyboard or a mouse binding.
824 ---------------------------
829 "event_state_mask": [
835 "input_type": "keyboard"
838 ---------------------------
842 This event is triggered when the connection to the ipc is about to shutdown
843 because of a user action such as a +restart+ or +exit+ command. The +change
844 (string)+ field indicates why the ipc is shutting down. It can be either
845 +"restart"+ or +"exit"+.
848 ---------------------------
852 ---------------------------
854 == See also (existing libraries)
858 For some languages, libraries are available (so you don’t have to implement
859 all this on your own). This list names some (if you wrote one, please let me
863 * i3 includes a headerfile +i3/ipc.h+ which provides you all constants.
864 * https://github.com/acrisci/i3ipc-glib
866 * https://github.com/drmgc/i3ipcpp
868 * https://github.com/mdirkse/i3ipc-go
870 * https://github.com/acrisci/i3ipc-gjs
872 * https://github.com/acrisci/i3ipc-lua
874 * https://metacpan.org/module/AnyEvent::I3
876 * https://github.com/acrisci/i3ipc-python
877 * https://github.com/whitelynx/i3ipc (not maintained)
878 * https://github.com/ziberna/i3-py (not maintained)
880 * https://github.com/veelenga/i3ipc-ruby
881 * https://github.com/badboy/i3-ipc (not maintained)
883 * https://github.com/tmerr/i3ipc-rs
885 * https://github.com/Armael/ocaml-i3ipc