Keyboard Layout Indicator and Switcher for Waybar (No Polling, No Extra Packages and Dependencies)

[gvozdemon]

Set the grp_led:scroll XKB option in your environment file. For example:

XKB_DEFAULT_LAYOUT=ru,us
XKB_DEFAULT_OPTIONS=grp:alt_shift_toggle,grp_led:scroll

This option lets us programmatically detect the current layout by reading 0 or 1 from /sys/class/leds/input*::scrolllock/brightness. Since sysfs files don't reliably trigger inotify events, we use polling—periodically reading the file—to track changes. We'll write a helper script named kb-layout that maps these values to short layout codes (e.g., en/ru) for display in Waybar.

#!/bin/sh
for led in /sys/class/leds/input*::scrolllock/brightness; do
    read -r state < "$led"
    [ "$state" = "1" ] && echo "EN" || echo "RU"
    exit 0
done

Next, add a custom/layout module to your Waybar configuration under "modules-right":

"modules-right": ["custom/layout", ...]

Configure the module as follows:

"custom/layout": {
    "format": "{text}",
    "exec": "/path/to/kb-layout",
    "on-click": "ydotool key 56:1 42:1 42:0 56:0",
    "interval": 1,
    "tooltip": false
},

Make sure to define the #custom-layout selector in your Waybar CSS configuration.
The layout module now shows the active keyboard layout. Refreshing once per second via lightweight polling, it adds virtually zero overhead to the system.
We can enhance the module to update instantly on click—both via signal and polling—eliminating the 1‑second delay:

"custom/layout": {
    "format": "{text}",
    "exec": "/path/to/kb-layout",
    "on-click": "ydotool key 56:1 42:1 42:0 56:0 && pkill -RTMIN+2 waybar",
    "interval": 1,
    "signal": 2,
    "tooltip": false
},

For cleaner configuration, extract the layout-switching command into a dedicated script. This script will toggle the keyboard layout and instantly refresh the Waybar indicator:

#!/bin/sh
ydotool key 56:1 42:1 42:0 56:0
pkill -RTMIN+2 waybar

Save it as kb-toggle and make it executable. Then simplify the Waybar module configuration:

"custom/layout": {
    "format": "{text}",
    "exec": "/path/to/kb-layout",
    "on-click": "/path/to/kb-toggle",
    "interval": 1,
    "signal": 2,
    "tooltip": false
},

[gvozdemon]

Update: I've replaced the old polling-based method with a cleaner solution:

No polling
No additional packages
Works out of the box with labwc on Debian

To switch from periodic polling to a pure signal-driven approach, simply change the interval value in your custom/layout module from 1 to "once":

"custom/layout": {
"format": "{text}",
"exec": "/path/to/kb-layout",
"on-click": "/path/to/kb-toggle",
"interval": "once",
"signal": 2,
"tooltip": false
},

To keep the layout indicator instantly up to date on window focus changes, configure the "wlr/taskbar" module to emit a refresh signal:

"wlr/taskbar": {
"on-update": "pkill -RTMIN+2 waybar"
},

Since Waybar receives taskbar updates on every focus/activation event, this hook triggers a signal-based refresh of the "custom/layout" module — eliminating the need for polling entirely.

At this point we have:
Instant layout toggle and refresh on panel click
Automatic indicator refresh on window focus changes

The final piece is keyboard-driven layout switching with instant visual feedback. Configure a keybinding in ~/.config/labwc/rc.xml:

<keybind key="W-Space">
  <action name="Execute" command="/path/to/kb-toggle"/>
</keybind>

Important: Avoid using Shift as part of the keybinding (e.g., Shift+Space). Labwc currently has known issues handling Shift-based bindings for layout switching . Instead, choose any other modifier combination — W-Space (Super+Space), A-Space (Alt+Space), or even CapsLock remapped via xkb work reliably.

Pressing the bound shortcut now:
Toggles the keyboard layout via kb-toggle
The script emits -RTMIN+2 to Waybar
Waybar instantly refreshes the custom/layout indicator

[stefonarch]

This is the very old polling hack which works only for 2 layouts unfortunately. Yesterday https://github.com/drougas/xkb-monitor came out and it's working fine, just xkb-monitor -n to display the layout and no polling needed.

[tsujan]

Yesterday https://github.com/drougas/xkb-monitor came out and it's working fine

It's superb. Works under labwc with lxqt-panel's Custom Command in various ways, with or without flags.

[gvozdemon]

I created a script kb-eng that forces the English keyboard layout on launch. It can be automatically triggered for specific applications via window rules in ~/.config/labwc/rc.xm

#!/bin/sh
for led in /sys/class/leds/input*::scrolllock/brightness; do
    [ -f "$led" ] || continue
    read -r state < "$led"
    [ "$state" = "0" ] && ydotool key 56:1 42:1 42:0 56:0
    break
done

<windowRule title="Foot">
      <action name="Execute" command="/path/to/kb-eng" />
    </windowRule>