Enable num-lock as default in Linux

Linux initializes most peripherals so that they'll be in a known state. This includes the keyboard: Linux's internal data about the keyboard had better match the LEDs, so what Linux does is to turn off the LEDs (as far as I recall, the CPU can't read the state of the LEDs on a PC keyboard) and declare all *Lock to be off.

I like to have NumLock on by default. For Linux text consoles, what I used to do¹ is to run

for t in /dev/tty[0-9]*; do setleds -D +num <$t; done

from a boot script (/etc/rc.local or /etc/init.d/50_local_setleds or wherever the distribution likes to put those).

Nowadays, at least on some distributions such as Debian, you can add LEDS=+num to /etc/console-tools/config (or /etc/kbd/config depending on which one you have).

The X window system has its own keyboard handling, so you need to deal with it separately. What I do is to switch caps lock permanently off (I don't have a Caps Lock key in my layout) and switch num lock permanently on (I don't have a Num Lock key in my layout, and the keypad keys send KP_1 and so on). If you want to retain the modifiers but make Num Lock default on, you can write a small program to call XKbLockModifiers to set the modifier inside X and XChangeKeyboardControl to set the physical LED.

¹ _{Used to, because I haven't bothered with text consoles in a while.}