Linux – How to get the keybind on a keyboard’s special FN key? Showkey and xev can’t find it

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I'm trying to map the special 'FN' key on a Logitech K360 keyboard to 'Mod3' in the i3wm window manager on Debian. However, I can't find the keycode for the 'FN' key. Showkey and xev don't return any value when 'FN' is pressed. However, the FN key does work and returns different single values in line with the FN default settings. For example, xev and showkey shows 'End' when I press the End key, but returns 'Pause' when I press FN+End.

Solaar doesn't seem to have any settings that help with this.

How do I get the keybind for 'FN'? Thanks.

Best Answer

This is not possible. The Fn key is handled by the keyboard, not by the operating system, which is not even aware of the existence of the Fn key. As far as the OS is concerned, End and Fn+End are two unrelated keys with different scancodes. The Fn key does not produce a scancode by itself and cannot be independently detected by the OS.

Related Solutions

Xmodmap for key combination – how to toggle the Fn behavior

I obtained the same result by swapping the keycodes between Fn+Fx and Fx where x is 1,2,...12.

Use xmodmap -pke to obtain a list of the current keycodes and keysymbols.
Then run xev and press F1 through F12 keeping note of its keycode.
Then make the swap in your ~/.Xmodmap file.

For e.g. in my system the result of (1):

keycode 67 = F1 F1 F1 F1 F1 F1 XF86Switch_VT_1
keycode 68 = F2 F2 F2 F2 F2 F2 XF86Switch_VT_2
keycode 69 = F3 F3 F3 F3 F3 F3 XF86Switch_VT_3
keycode 70 = F4 F4 F4 F4 F4 F4 XF86Switch_VT_4
...

keycode 121 = XF86AudioMute NoSymbol XF86AudioMute
keycode 122 = XF86AudioLowerVolume NoSymbol XF86AudioLowerVolume
keycode 123 = XF86AudioRaiseVolume NoSymbol XF86AudioRaiseVolume
keycode 198 = XF86AudioMicMute NoSymbol XF86AudioMicMute
..

Then I swapped it in ~/.Xmodmap:

keycode 121 = F1 F1 F1 F1 F1 F1 XF86Switch_VT_1
keycode 122 = F2 F2 F2 F2 F2 F2 XF86Switch_VT_2
keycode 123 = F3 F3 F3 F3 F3 F3 XF86Switch_VT_3
keycode 198 = F4 F4 F4 F4 F4 F4 XF86Switch_VT_4
...


keycode 67 = XF86AudioMute NoSymbol XF86AudioMute
keycode 68 = XF86AudioLowerVolume NoSymbol XF86AudioLowerVolume
keycode 69 = XF86AudioRaiseVolume NoSymbol XF86AudioRaiseVolume
keycode 70 = XF86AudioMicMute NoSymbol XF86AudioMicMute
...

Then to take affect run xmodmap ~/.Xmodmap.

Best Answer

Related Solutions

Xmodmap for key combination – how to toggle the Fn behavior

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