led-indicator

#!/bin/bash

# this one could make good use of trap

# other interesting triggers are possible, see
# grep LEDS_TRIGGER /boot/config-$(uname -r)
# ls /lib/modules/$(uname -r)/kernel/drivers/leds/trigger/
# modprobe what-you-want
# echo what-you-want > /sys/class/leds/*capslock/trigger
# for details refer to https://github.com/torvalds/linux/tree/master/drivers/leds/trigger

if [ ! 0 -eq `id -u` ]; then
    echo "must run as root"
    exit 1
fi

# if the keyboard has only one LED, blink only that
lsusb |grep Apple.*Keyboard >/dev/null
if [ $? = 0 ]; then CYCLOP=1; else CYCLOP=0; fi

for a in setleds sleep; do
    hash $a >/dev/null
    if [ ! $? -eq 0 ]; then
        echo $a not found
        exit 1
    fi
done

if [ $CYCLOP = 1 ]; then
    while (sleep $(echo 1 - $(date +.%N)|bc -l)); do
        setleds -L +caps < /dev/console
        sleep 0.1
        setleds -L -caps < /dev/console
    done
else 
    while (sleep $(echo 1 - $(date +.%N)|bc -l)); do
        setleds -L +num < /dev/console
        sleep 0.1
        setleds -L -num < /dev/console
        setleds -L +caps < /dev/console
        sleep 0.1
        setleds -L -caps < /dev/console
        setleds -L +scroll < /dev/console
        sleep 0.1
        setleds -L -scroll < /dev/console
    done
fi