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 are the following:
56 The payload of the message is a command for i3 (like the commands you
57 can bind to keys in the configuration file) and will be executed
58 directly after receiving it.
60 Gets the current workspaces. The reply will be a JSON-encoded list of
61 workspaces (see the reply section).
63 Subscribes your connection to certain events. See <<events>> for a
64 description of this message and the concept of events.
66 Gets the current outputs. The reply will be a JSON-encoded list of outputs
67 (see the reply section).
69 Gets the layout tree. i3 uses a tree as data structure which includes
70 every container. The reply will be the JSON-encoded tree (see the reply
73 Gets a list of marks (identifiers for containers to easily jump to them
74 later). The reply will be a JSON-encoded list of window marks (see
77 Gets the configuration (as JSON map) of the workspace bar with the
78 given ID. If no ID is provided, an array with all configured bar IDs is
81 Gets the version of i3. The reply will be a JSON-encoded dictionary
82 with the major, minor, patch and human-readable version.
83 GET_BINDING_MODES (8)::
84 Gets a list of currently configured binding modes.
86 So, a typical message could look like this:
87 --------------------------------------------------
88 "i3-ipc" <message length> <message type> <payload>
89 --------------------------------------------------
92 ------------------------------------------------------------------------------
93 00000000 69 33 2d 69 70 63 04 00 00 00 00 00 00 00 65 78 |i3-ipc........ex|
95 ------------------------------------------------------------------------------
97 To generate and send such a message, you could use the following code in Perl:
98 ------------------------------------------------------------
99 sub format_ipc_command {
102 # Get the real byte count (vs. amount of characters)
103 { use bytes; $len = length($msg); }
104 return "i3-ipc" . pack("LL", $len, 0) . $msg;
107 $sock->write(format_ipc_command("exit"));
108 ------------------------------------------------------------------------------
110 == Receiving replies from i3
112 Replies from i3 usually consist of a simple string (the length of the string
113 is the message_length, so you can consider them length-prefixed) which in turn
114 contain the JSON serialization of a data structure. For example, the
115 GET_WORKSPACES message returns an array of workspaces (each workspace is a map
116 with certain attributes).
120 The reply format is identical to the normal message format. There also is
121 the magic string, then the message length, then the message type and the
124 The following reply types are implemented:
127 Confirmation/Error code for the COMMAND message.
129 Reply to the GET_WORKSPACES message.
131 Confirmation/Error code for the SUBSCRIBE message.
133 Reply to the GET_OUTPUTS message.
135 Reply to the GET_TREE message.
137 Reply to the GET_MARKS message.
139 Reply to the GET_BAR_CONFIG message.
141 Reply to the GET_VERSION message.
143 Reply to the GET_BINDING_MODES message.
147 The reply consists of a list of serialized maps for each command that was
148 parsed. Each has the property +success (bool)+ and may also include a
149 human-readable error message in the property +error (string)+.
153 [{ "success": true }]
158 The reply consists of a serialized list of workspaces. Each workspace has the
159 following properties:
162 The logical number of the workspace. Corresponds to the command
163 to switch to this workspace. For named workspaces, this will be -1.
165 The name of this workspace (by default num+1), as changed by the
166 user. Encoded in UTF-8.
168 Whether this workspace is currently visible on an output (multiple
169 workspaces can be visible at the same time).
171 Whether this workspace currently has the focus (only one workspace
172 can have the focus at the same time).
174 Whether a window on this workspace has the "urgent" flag set.
176 The rectangle of this workspace (equals the rect of the output it
177 is on), consists of x, y, width, height.
179 The video output this workspace is on (LVDS1, VGA1, …).
217 The reply consists of a single serialized map. The only property is
218 +success (bool)+, indicating whether the subscription was successful (the
219 default) or whether a JSON parse error occurred.
228 The reply consists of a serialized list of outputs. Each output has the
229 following properties:
232 The name of this output (as seen in +xrandr(1)+). Encoded in UTF-8.
234 Whether this output is currently active (has a valid mode).
236 Whether this output is currently the primary output.
237 current_workspace (string)::
238 The name of the current workspace that is visible on this output. +null+ if
239 the output is not active.
241 The rectangle of this output (equals the rect of the output it
242 is on), consists of x, y, width, height.
250 "current_workspace": "4",
261 "current_workspace": "1",
274 The reply consists of a serialized tree. Each node in the tree (representing
275 one container) has at least the properties listed below. While the nodes might
276 have more properties, please do not use any properties which are not documented
277 here. They are not yet finalized and will probably change!
280 The internal ID (actually a C pointer value) of this container. Do not
281 make any assumptions about it. You can use it to (re-)identify and
282 address containers when talking to i3.
284 The internal name of this container. For all containers which are part
285 of the tree structure down to the workspace contents, this is set to a
286 nice human-readable name of the container.
287 For containers that have an X11 window, the content is the title
288 (_NET_WM_NAME property) of that window.
289 For all other containers, the content is not defined (yet).
291 Type of this container. Can be one of "root", "output", "con",
292 "floating_con", "workspace" or "dockarea".
294 Can be either "normal", "none" or "pixel", depending on the
295 container’s border style.
296 current_border_width (integer)::
297 Number of pixels of the border width.
299 Can be either "splith", "splitv", "stacked", "tabbed", "dockarea" or
301 Other values might be possible in the future, should we add new
303 orientation (string)::
304 Can be either "none" (for non-split containers), "horizontal" or
306 THIS FIELD IS OBSOLETE. It is still present, but your code should not
307 use it. Instead, rely on the layout field.
309 The percentage which this container takes in its parent. A value of
310 +null+ means that the percent property does not make sense for this
311 container, for example for the root container.
313 The absolute display coordinates for this container. Display
314 coordinates means that when you have two 1600x1200 monitors on a single
315 X11 Display (the standard way), the coordinates of the first window on
316 the second monitor are +{ "x": 1600, "y": 0, "width": 1600, "height":
319 The coordinates of the *actual client window* inside its container.
320 These coordinates are relative to the container and do not include the
321 window decoration (which is actually rendered on the parent container).
322 So, when using the +default+ layout, you will have a 2 pixel border on
323 each side, making the window_rect +{ "x": 2, "y": 0, "width": 632,
324 "height": 366 }+ (for example).
326 The coordinates of the *window decoration* inside its container. These
327 coordinates are relative to the container and do not include the actual
330 The original geometry the window specified when i3 mapped it. Used when
331 switching a window to floating mode, for example.
333 The X11 window ID of the *actual client window* inside this container.
334 This field is set to null for split containers or otherwise empty
335 containers. This ID corresponds to what xwininfo(1) and other
336 X11-related tools display (usually in hex).
338 Whether this container (window or workspace) has the urgency hint set.
340 Whether this container is currently focused.
341 focus (array of integer)::
342 List of child node IDs (see +nodes+, +floating_nodes+ and +id+) in focus
343 order. Traversing the tree by following the first entry in this array
344 will result in eventually reaching the one node with +focused+ set to
346 nodes (array of node)::
347 The tiling (i.e. non-floating) child containers of this node.
348 floating_nodes (array of node)::
349 The floating child containers of this node. Only non-empty on nodes with
352 Please note that in the following example, I have left out some keys/values
353 which are not relevant for the type of the node. Otherwise, the example would
354 be by far too long (it already is quite long, despite showing only 1 window and
357 It is useful to have an overview of the structure before taking a look at the
371 -----------------------
398 "layout": "dockarea",
399 "orientation": "vertical",
422 "orientation": "horizontal",
429 "floating_nodes": [],
453 "name": "bottomdock",
454 "layout": "dockarea",
455 "orientation": "vertical",
482 ------------------------
486 The reply consists of a single array of strings for each container that has a
487 mark. A mark can only be set on one container, so the array is unique.
488 The order of that array is undefined.
490 If no window has a mark the response will be the empty array [].
494 This can be used by third-party workspace bars (especially i3bar, but others
495 are free to implement compatible alternatives) to get the +bar+ block
496 configuration from i3.
498 Depending on the input, the reply is either:
501 An array of configured bar IDs
503 A JSON map containing the configuration for the specified bar.
505 Each bar configuration has the following properties:
508 The ID for this bar. Included in case you request multiple
509 configurations and want to differentiate the different replies.
511 Either +dock+ (the bar sets the dock window type) or +hide+ (the bar
512 does not show unless a specific key is pressed).
514 Either +bottom+ or +top+ at the moment.
515 status_command (string)::
516 Command which will be run to generate a statusline. Each line on stdout
517 of this command will be displayed in the bar. At the moment, no
518 formatting is supported.
520 The font to use for text on the bar.
521 workspace_buttons (boolean)::
522 Display workspace buttons or not? Defaults to true.
523 binding_mode_indicator (boolean)::
524 Display the mode indicator or not? Defaults to true.
526 Should the bar enable verbose output for debugging? Defaults to false.
528 Contains key/value pairs of colors. Each value is a color code in hex,
529 formatted #rrggbb (like in HTML).
531 The following colors can be configured at the moment:
534 Background color of the bar.
536 Text color to be used for the statusline.
538 Text color to be used for the separator.
540 Background color of the bar on the currently focused monitor output.
542 Text color to be used for the statusline on the currently focused
545 Text color to be used for the separator on the currently focused
547 focused_workspace_text/focused_workspace_bg/focused_workspace_border::
548 Text/background/border color for a workspace button when the workspace
550 active_workspace_text/active_workspace_bg/active_workspace_border::
551 Text/background/border color for a workspace button when the workspace
552 is active (visible) on some output, but the focus is on another one.
553 You can only tell this apart from the focused workspace when you are
554 using multiple monitors.
555 inactive_workspace_text/inactive_workspace_bg/inactive_workspace_border::
556 Text/background/border color for a workspace button when the workspace
557 does not have focus and is not active (visible) on any output. This
558 will be the case for most workspaces.
559 urgent_workspace_text/urgent_workspace_bg/urgent_workspace_border::
560 Text/background/border color for workspaces which contain at least one
561 window with the urgency hint set.
562 binding_mode_text/binding_mode_bg/binding_mode_border::
563 Text/background/border color for the binding mode indicator.
566 *Example of configured bars:*
571 *Example of bar configuration:*
576 "position": "bottom",
577 "status_command": "i3status",
578 "font": "-misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1",
579 "workspace_buttons": true,
580 "binding_mode_indicator": true,
583 "background": "#c0c0c0",
584 "statusline": "#00ff00",
585 "focused_workspace_text": "#ffffff",
586 "focused_workspace_bg": "#000000"
593 The reply consists of a single JSON dictionary with the following keys:
596 The major version of i3, such as +4+.
598 The minor version of i3, such as +2+. Changes in the IPC interface (new
599 features) will only occur with new minor (or major) releases. However,
600 bugfixes might be introduced in patch releases, too.
602 The patch version of i3, such as +1+ (when the complete version is
603 +4.2.1+). For versions such as +4.2+, patch will be set to +0+.
604 human_readable (string)::
605 A human-readable version of i3 containing the precise git version,
606 build date and branch name. When you need to display the i3 version to
607 your users, use the human-readable version whenever possible (since
608 this is what +i3 --version+ displays, too).
609 loaded_config_file_name (string)::
610 The current config path.
615 "human_readable" : "4.2-169-gf80b877 (2012-08-05, branch \"next\")",
616 "loaded_config_file_name" : "/home/hwangcc23/.i3/config",
623 === BINDING_MODES reply
625 The reply consists of an array of all currently configured binding modes.
628 ---------------------
629 ["default", "resize"]
630 ---------------------
636 To get informed when certain things happen in i3, clients can subscribe to
637 events. Events consist of a name (like "workspace") and an event reply type
638 (like I3_IPC_EVENT_WORKSPACE). The events sent by i3 are in the same format
639 as replies to specific commands. However, the highest bit of the message type
640 is set to 1 to indicate that this is an event reply instead of a normal reply.
642 Caveat: As soon as you subscribe to an event, it is not guaranteed any longer
643 that the requests to i3 are processed in order. This means, the following
644 situation can happen: You send a GET_WORKSPACES request but you receive a
645 "workspace" event before receiving the reply to GET_WORKSPACES. If your
646 program does not want to cope which such kinds of race conditions (an
647 event based library may not have a problem here), I suggest you create a
648 separate connection to receive events.
650 === Subscribing to events
652 By sending a message of type SUBSCRIBE with a JSON-encoded array as payload
653 you can register to an event.
656 ---------------------------------
658 payload: [ "workspace", "output" ]
659 ---------------------------------
664 The numbers in parenthesis is the event type (keep in mind that you need to
665 strip the highest bit first).
668 Sent when the user switches to a different workspace, when a new
669 workspace is initialized or when a workspace is removed (because the
670 last client vanished).
672 Sent when RandR issues a change notification (of either screens,
673 outputs, CRTCs or output properties).
675 Sent whenever i3 changes its binding mode.
677 Sent when a client's window is successfully reparented (that is when i3
678 has finished fitting it into a container), when a window received input
679 focus or when certain properties of the window have changed.
680 barconfig_update (4)::
681 Sent when the hidden_state or mode field in the barconfig of any bar
682 instance was updated and when the config is reloaded.
684 Sent when a configured command binding is triggered with the keyboard or
687 Sent when the ipc shuts down because of a restart or exit by user command
690 --------------------------------------------------------------------
691 # the appropriate 4 bytes read from the socket are stored in $input
693 # unpack a 32-bit unsigned integer
694 my $message_type = unpack("L", $input);
696 # check if the highest bit is 1
697 my $is_event = (($message_type >> 31) == 1);
700 my $event_type = ($message_type & 0x7F);
703 say "Received event of type $event_type";
705 --------------------------------------------------------------------
709 This event consists of a single serialized map containing a property
710 +change (string)+ which indicates the type of the change ("focus", "init",
711 "empty", "urgent", "reload", "rename", "restored", "move"). A
712 +current (object)+ property will be present with the affected workspace
713 whenever the type of event affects a workspace (otherwise, it will be +null).
715 When the change is "focus", an +old (object)+ property will be present with the
716 previous workspace. When the first switch occurs (when i3 focuses the
717 workspace visible at the beginning) there is no previous workspace, and the
718 +old+ property will be set to +null+. Also note that if the previous is empty
719 it will get destroyed when switching, but will still be present in the "old"
723 ---------------------
737 ---------------------
741 This event consists of a single serialized map containing a property
742 +change (string)+ which indicates the type of the change (currently only
746 ---------------------------
747 { "change": "unspecified" }
748 ---------------------------
752 This event consists of a single serialized map containing a property
753 +change (string)+ which holds the name of current mode in use. The name
754 is the same as specified in config when creating a mode. The default
755 mode is simply named default. It contains a second property, +pango_markup+, which
756 defines whether pango markup shall be used for displaying this mode.
759 ---------------------------
764 ---------------------------
768 This event consists of a single serialized map containing a property
769 +change (string)+ which indicates the type of the change
771 * +new+ – the window has become managed by i3
772 * +close+ – the window has closed
773 * +focus+ – the window has received input focus
774 * +title+ – the window's title has changed
775 * +fullscreen_mode+ – the window has entered or exited fullscreen mode
776 * +move+ – the window has changed its position in the tree
777 * +floating+ – the window has transitioned to or from floating
778 * +urgent+ – the window has become urgent or lost its urgent status
779 * +mark+ – a mark has been added to or removed from the window
781 Additionally a +container (object)+ field will be present, which consists
782 of the window's parent container. Be aware that for the "new" event, the
783 container will hold the initial name of the newly reparented window (e.g.
784 if you run urxvt with a shell that changes the title, you will still at
785 this point get the window title as "urxvt").
788 ---------------------------
797 ---------------------------
799 === barconfig_update event
801 This event consists of a single serialized map reporting on options from the
802 barconfig of the specified bar_id that were updated in i3. This event is the
803 same as a +GET_BAR_CONFIG+ reply for the bar with the given id.
807 This event consists of a single serialized map reporting on the details of a
808 binding that ran a command because of user input. The +change (string)+ field
809 indicates what sort of binding event was triggered (right now it will always be
810 +"run"+ but may be expanded in the future).
812 The +binding (object)+ field contains details about the binding that was run:
815 The i3 command that is configured to run for this binding.
816 event_state_mask (array of strings)::
817 The group and modifier keys that were configured with this binding.
818 input_code (integer)::
819 If the binding was configured with +bindcode+, this will be the key code
820 that was given for the binding. If the binding is a mouse binding, it will be
821 the number of the mouse button that was pressed. Otherwise it will be 0.
822 symbol (string or null)::
823 If this is a keyboard binding that was configured with +bindsym+, this
824 field will contain the given symbol. Otherwise it will be +null+.
825 input_type (string)::
826 This will be +"keyboard"+ or +"mouse"+ depending on whether or not this was
827 a keyboard or a mouse binding.
830 ---------------------------
835 "event_state_mask": [
841 "input_type": "keyboard"
844 ---------------------------
848 This event is triggered when the connection to the ipc is about to shutdown
849 because of a user action such as a +restart+ or +exit+ command. The +change
850 (string)+ field indicates why the ipc is shutting down. It can be either
851 +"restart"+ or +"exit"+.
854 ---------------------------
858 ---------------------------
860 == See also (existing libraries)
864 For some languages, libraries are available (so you don’t have to implement
865 all this on your own). This list names some (if you wrote one, please let me
869 * i3 includes a headerfile +i3/ipc.h+ which provides you all constants.
870 * https://github.com/acrisci/i3ipc-glib
872 * https://github.com/drmgc/i3ipcpp
874 * https://github.com/mdirkse/i3ipc-go
876 * https://github.com/acrisci/i3ipc-gjs
878 * https://github.com/acrisci/i3ipc-lua
880 * https://metacpan.org/module/AnyEvent::I3
882 * https://github.com/acrisci/i3ipc-python
883 * https://github.com/whitelynx/i3ipc (not maintained)
884 * https://github.com/ziberna/i3-py (not maintained)
886 * https://github.com/veelenga/i3ipc-ruby
887 * https://github.com/badboy/i3-ipc (not maintained)
889 * https://github.com/tmerr/i3ipc-rs
891 * https://github.com/Armael/ocaml-i3ipc