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.
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 ------------------------
476 The reply consists of a single array of strings for each container that has a
477 mark. A mark can only be set on one container, so the array is unique.
478 The order of that array is undefined.
480 If no window has a mark the response will be the empty array [].
484 This can be used by third-party workspace bars (especially i3bar, but others
485 are free to implement compatible alternatives) to get the +bar+ block
486 configuration from i3.
488 Depending on the input, the reply is either:
491 An array of configured bar IDs
493 A JSON map containing the configuration for the specified bar.
495 Each bar configuration has the following properties:
498 The ID for this bar. Included in case you request multiple
499 configurations and want to differentiate the different replies.
501 Either +dock+ (the bar sets the dock window type) or +hide+ (the bar
502 does not show unless a specific key is pressed).
504 Either +bottom+ or +top+ at the moment.
505 status_command (string)::
506 Command which will be run to generate a statusline. Each line on stdout
507 of this command will be displayed in the bar. At the moment, no
508 formatting is supported.
510 The font to use for text on the bar.
511 workspace_buttons (boolean)::
512 Display workspace buttons or not? Defaults to true.
513 binding_mode_indicator (boolean)::
514 Display the mode indicator or not? Defaults to true.
516 Should the bar enable verbose output for debugging? Defaults to false.
518 Contains key/value pairs of colors. Each value is a color code in hex,
519 formatted #rrggbb (like in HTML).
521 The following colors can be configured at the moment:
524 Background color of the bar.
526 Text color to be used for the statusline.
528 Text color to be used for the separator.
530 Background color of the bar on the currently focused monitor output.
532 Text color to be used for the statusline on the currently focused
535 Text color to be used for the separator on the currently focused
537 focused_workspace_text/focused_workspace_bg/focused_workspace_border::
538 Text/background/border color for a workspace button when the workspace
540 active_workspace_text/active_workspace_bg/active_workspace_border::
541 Text/background/border color for a workspace button when the workspace
542 is active (visible) on some output, but the focus is on another one.
543 You can only tell this apart from the focused workspace when you are
544 using multiple monitors.
545 inactive_workspace_text/inactive_workspace_bg/inactive_workspace_border::
546 Text/background/border color for a workspace button when the workspace
547 does not have focus and is not active (visible) on any output. This
548 will be the case for most workspaces.
549 urgent_workspace_text/urgent_workspace_bg/urgent_workspace_border::
550 Text/background/border color for workspaces which contain at least one
551 window with the urgency hint set.
552 binding_mode_text/binding_mode_bg/binding_mode_border::
553 Text/background/border color for the binding mode indicator.
556 *Example of configured bars:*
561 *Example of bar configuration:*
566 "position": "bottom",
567 "status_command": "i3status",
568 "font": "-misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1",
569 "workspace_buttons": true,
570 "binding_mode_indicator": true,
573 "background": "#c0c0c0",
574 "statusline": "#00ff00",
575 "focused_workspace_text": "#ffffff",
576 "focused_workspace_bg": "#000000"
583 The reply consists of a single JSON dictionary with the following keys:
586 The major version of i3, such as +4+.
588 The minor version of i3, such as +2+. Changes in the IPC interface (new
589 features) will only occur with new minor (or major) releases. However,
590 bugfixes might be introduced in patch releases, too.
592 The patch version of i3, such as +1+ (when the complete version is
593 +4.2.1+). For versions such as +4.2+, patch will be set to +0+.
594 human_readable (string)::
595 A human-readable version of i3 containing the precise git version,
596 build date and branch name. When you need to display the i3 version to
597 your users, use the human-readable version whenever possible (since
598 this is what +i3 --version+ displays, too).
599 loaded_config_file_name (string)::
600 The current config path.
605 "human_readable" : "4.2-169-gf80b877 (2012-08-05, branch \"next\")",
606 "loaded_config_file_name" : "/home/hwangcc23/.i3/config",
613 === BINDING_MODES reply
615 The reply consists of an array of all currently configured binding modes.
618 ---------------------
619 ["default", "resize"]
620 ---------------------
626 To get informed when certain things happen in i3, clients can subscribe to
627 events. Events consist of a name (like "workspace") and an event reply type
628 (like I3_IPC_EVENT_WORKSPACE). The events sent by i3 are in the same format
629 as replies to specific commands. However, the highest bit of the message type
630 is set to 1 to indicate that this is an event reply instead of a normal reply.
632 Caveat: As soon as you subscribe to an event, it is not guaranteed any longer
633 that the requests to i3 are processed in order. This means, the following
634 situation can happen: You send a GET_WORKSPACES request but you receive a
635 "workspace" event before receiving the reply to GET_WORKSPACES. If your
636 program does not want to cope which such kinds of race conditions (an
637 event based library may not have a problem here), I suggest you create a
638 separate connection to receive events.
640 === Subscribing to events
642 By sending a message of type SUBSCRIBE with a JSON-encoded array as payload
643 you can register to an event.
646 ---------------------------------
648 payload: [ "workspace", "output" ]
649 ---------------------------------
654 The numbers in parenthesis is the event type (keep in mind that you need to
655 strip the highest bit first).
658 Sent when the user switches to a different workspace, when a new
659 workspace is initialized or when a workspace is removed (because the
660 last client vanished).
662 Sent when RandR issues a change notification (of either screens,
663 outputs, CRTCs or output properties).
665 Sent whenever i3 changes its binding mode.
667 Sent when a client's window is successfully reparented (that is when i3
668 has finished fitting it into a container), when a window received input
669 focus or when certain properties of the window have changed.
670 barconfig_update (4)::
671 Sent when the hidden_state or mode field in the barconfig of any bar
672 instance was updated and when the config is reloaded.
674 Sent when a configured command binding is triggered with the keyboard or
677 Sent when the ipc shuts down because of a restart or exit by user command
680 --------------------------------------------------------------------
681 # the appropriate 4 bytes read from the socket are stored in $input
683 # unpack a 32-bit unsigned integer
684 my $message_type = unpack("L", $input);
686 # check if the highest bit is 1
687 my $is_event = (($message_type >> 31) == 1);
690 my $event_type = ($message_type & 0x7F);
693 say "Received event of type $event_type";
695 --------------------------------------------------------------------
699 This event consists of a single serialized map containing a property
700 +change (string)+ which indicates the type of the change ("focus", "init",
701 "empty", "urgent", "reload", "rename", "restored", "move"). A
702 +current (object)+ property will be present with the affected workspace
703 whenever the type of event affects a workspace (otherwise, it will be +null).
705 When the change is "focus", an +old (object)+ property will be present with the
706 previous workspace. When the first switch occurs (when i3 focuses the
707 workspace visible at the beginning) there is no previous workspace, and the
708 +old+ property will be set to +null+. Also note that if the previous is empty
709 it will get destroyed when switching, but will still be present in the "old"
713 ---------------------
727 ---------------------
731 This event consists of a single serialized map containing a property
732 +change (string)+ which indicates the type of the change (currently only
736 ---------------------------
737 { "change": "unspecified" }
738 ---------------------------
742 This event consists of a single serialized map containing a property
743 +change (string)+ which holds the name of current mode in use. The name
744 is the same as specified in config when creating a mode. The default
745 mode is simply named default. It contains a second property, +pango_markup+, which
746 defines whether pango markup shall be used for displaying this mode.
749 ---------------------------
754 ---------------------------
758 This event consists of a single serialized map containing a property
759 +change (string)+ which indicates the type of the change
761 * +new+ – the window has become managed by i3
762 * +close+ – the window has closed
763 * +focus+ – the window has received input focus
764 * +title+ – the window's title has changed
765 * +fullscreen_mode+ – the window has entered or exited fullscreen mode
766 * +move+ – the window has changed its position in the tree
767 * +floating+ – the window has transitioned to or from floating
768 * +urgent+ – the window has become urgent or lost its urgent status
769 * +mark+ – a mark has been added to or removed from the window
771 Additionally a +container (object)+ field will be present, which consists
772 of the window's parent container. Be aware that for the "new" event, the
773 container will hold the initial name of the newly reparented window (e.g.
774 if you run urxvt with a shell that changes the title, you will still at
775 this point get the window title as "urxvt").
778 ---------------------------
787 ---------------------------
789 === barconfig_update event
791 This event consists of a single serialized map reporting on options from the
792 barconfig of the specified bar_id that were updated in i3. This event is the
793 same as a +GET_BAR_CONFIG+ reply for the bar with the given id.
797 This event consists of a single serialized map reporting on the details of a
798 binding that ran a command because of user input. The +change (string)+ field
799 indicates what sort of binding event was triggered (right now it will always be
800 +"run"+ but may be expanded in the future).
802 The +binding (object)+ field contains details about the binding that was run:
805 The i3 command that is configured to run for this binding.
806 event_state_mask (array of strings)::
807 The group and modifier keys that were configured with this binding.
808 input_code (integer)::
809 If the binding was configured with +bindcode+, this will be the key code
810 that was given for the binding. If the binding is a mouse binding, it will be
811 the number of the mouse button that was pressed. Otherwise it will be 0.
812 symbol (string or null)::
813 If this is a keyboard binding that was configured with +bindsym+, this
814 field will contain the given symbol. Otherwise it will be +null+.
815 input_type (string)::
816 This will be +"keyboard"+ or +"mouse"+ depending on whether or not this was
817 a keyboard or a mouse binding.
820 ---------------------------
825 "event_state_mask": [
831 "input_type": "keyboard"
834 ---------------------------
838 This event is triggered when the connection to the ipc is about to shutdown
839 because of a user action such as a +restart+ or +exit+ command. The +change
840 (string)+ field indicates why the ipc is shutting down. It can be either
841 +"restart"+ or +"exit"+.
844 ---------------------------
848 ---------------------------
850 == See also (existing libraries)
854 For some languages, libraries are available (so you don’t have to implement
855 all this on your own). This list names some (if you wrote one, please let me
859 * i3 includes a headerfile +i3/ipc.h+ which provides you all constants.
860 * https://github.com/acrisci/i3ipc-glib
862 * https://github.com/drmgc/i3ipcpp
864 * https://github.com/mdirkse/i3ipc-go
866 * https://github.com/acrisci/i3ipc-gjs
868 * https://github.com/acrisci/i3ipc-lua
870 * https://metacpan.org/module/AnyEvent::I3
872 * https://github.com/acrisci/i3ipc-python
873 * https://github.com/whitelynx/i3ipc (not maintained)
874 * https://github.com/ziberna/i3-py (not maintained)
876 * https://github.com/veelenga/i3ipc-ruby
877 * https://github.com/badboy/i3-ipc (not maintained)
879 * https://github.com/tmerr/i3ipc-rs
881 * https://github.com/Armael/ocaml-i3ipc
projects / i3 / i3.github.io / blob