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How do I disable multiple chosen keys like Ctrl & Caps Lock from boot on Debian 11?

Mainly so they can't be used for system commands like opening the terminal or whatever else.

Fco Javier Balón
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1 Answers1

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This SuperUser article looks like it answers your question - It'll be the same principle

For me on Debian 12 (Bookworm), running xev -event keyboard from a terminal :

Pressing down the Ctrl key shows:

KeyPress event, serial 28, synthetic NO, window 0x5c00001,
    root 0x5ae, subw 0x0, time 2231447, (-655,427), root:(794,709),
    state 0x10, keycode 37 (keysym 0xffe3, Control_L), same_screen YES,
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False

and releasing the Ctrl key shows:

KeyRelease event, serial 28, synthetic NO, window 0x5c00001,
    root 0x5ae, subw 0x0, time 2231560, (-655,427), root:(794,709),
    state 0x14, keycode 37 (keysym 0xffe3, Control_L), same_screen YES,
    XLookupString gives 0 bytes: 
    XFilterEvent returns: False

I would then substitute <value> in:

xmodmap -e 'keycode <value>='

with

xmodmap -e 'keycode 37='

For me:

  • Ctrl = 37
  • Shift = 50
  • Alt = 64
  • Caps Lock = 66
  • Win/Command = 133

(using the backup method below actually gives you a list of all the mappings if you run it then run cat ~/originalkeymap.xmod !)

This other SuperUser answer also demonstrates how to reverse it (log out and back in?!) and also back up the existing key map before making any changes - Always a good idea to test!

Backup

xmodmap -pke > ~/originalkeymap.xmod

Restore

xmodmap ~/originalkeymap.xmod

You may need to consider what would happen if someone could disconnect and reconnect the keyboard, and also if they attached a second keyboard - I.e. secure your environment.

Aubs
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