Recover a Linux console keyboard with kbd_mode

You will identify a Linux virtual console's current keyboard mode and, when necessary, return it to UTF-8 mode with kbd_mode. This is a recovery tool for a console left in the wrong state, not a general keyboard customisation command. Allow about ten minutes. You need the kbd package and access to the target console; changing a console's mode normally requires root.

The examples match kbd 2.6.4-2ubuntu2 installed on this machine. The installed command accepts long options as well as the short forms shown in the original manual page. Your package may use a different version, so check its local help before putting a command into a recovery script.

1. Confirm the command and package version

Start with checks that do not change keyboard state:

$ command -v kbd_mode
/usr/bin/kbd_mode
$ kbd_mode --version
kbd_mode from kbd 2.6.4

The version output and package revision are separate: this host reports kbd_mode from kbd 2.6.4 and the package manager reports 2.6.4-2ubuntu2. Record the command version when troubleshooting a machine with older tooling.

2. Report the current mode

Run kbd_mode without a mode option while you are logged in on the console you want to inspect:

$ kbd_mode
UTF-8

The underlying manual describes the report as RAW, MEDIUMRAW or XLATE; the installed version prints the corresponding current state in its own wording, such as UTF-8. The command reads the console associated with standard input when -C is absent. A shell reached through SSH usually does not have the physical console as its standard input, so specify the console device explicitly there.

Do not mistake a terminal emulator for a virtual console. A desktop terminal and an SSH pseudo-terminal are not automatically the console whose keyboard is misbehaving.

3. Name the console explicitly when needed

Use -C with the device for the target Linux console. For example, from a privileged recovery shell:

# kbd_mode --console=/dev/tty1
UTF-8

The short equivalent is kbd_mode -C /dev/tty1. The option selects which console is inspected or changed; it does not switch your current shell to that console. Replace /dev/tty1 with the actual target device. Check the device before acting:

# test -c /dev/tty1 && echo 'character device exists'
character device exists
# ls -l /dev/tty1
crw--w---- 1 root tty ... /dev/tty1

The exact owner, group and permission bits vary. If the device does not exist, stop and identify the active console rather than guessing. A bad device path produces an error; it does not diagnose another console.

4. Restore the normal UTF-8 mode

If a program has left the target console unusable and you have confirmed the device, set UTF-8 mode:

# kbd_mode --unicode --console=/dev/tty1

--unicode is the long form of -u. In this mode, the kernel receives Unicode characters encoded as one, two or three UTF-8 bytes, and the key mapping loaded by loadkeys is used. The command normally prints no success message, so check its exit status immediately:

# status=$?
# printf 'kbd_mode exit status: %s\n' "$status"
kbd_mode exit status: 0
# kbd_mode --console=/dev/tty1
UTF-8

This changes console state but does not rewrite keymaps or alter boot configuration. If the first command fails, preserve the error text and investigate permissions or the device path before trying another mode.

5. Understand the other modes before touching them

kbd_mode has four mode selectors:

• -u or --unicode: UTF-8 mode.
• -a or --ascii: ASCII mode, called XLATE by the traditional manual.
• -k or --keycode: keycode or MEDIUMRAW mode.
• -s or --scancode: scancode or RAW mode.

Switching between ASCII and Unicode is the ordinary compatibility change. The manual warns that changing to or from the raw and keycode modes will probably make the keyboard unusable. Do not use -k or -s as experiments on a remote rescue session.

6. Recover if the console remains wrong

First return to Unicode without force, using the exact device:

# kbd_mode --unicode --console=/dev/tty1
# kbd_mode --console=/dev/tty1
UTF-8

If the console is still displaying unusable input, reconnect through an independent path such as SSH or another virtual console, confirm that you selected the right /dev/ttyN, and inspect the keymap with loadkeys. kbd_mode cannot repair a wrong keymap. Avoid stacking random -f changes: each one can make the affected console harder to control.

For a script, keep the target explicit and stop on failure:

#!/bin/sh
set -eu
console=${1:-/dev/tty1}
kbd_mode --unicode --console="$console"
kbd_mode --console="$console"

Pass a known device, such as /dev/tty1, rather than accepting untrusted input in a privileged wrapper. This command changes terminal behaviour and should not be exposed as an unrestricted service.