Example Bash Monitoring of `showkey` Utility

showkey-monitor.sh

#!/bin/bash

STOP=0

trap 'echo "Caught Ctrl+C, cleaning up..."; STOP=1; cleanup; exit 0' SIGINT

cleanup() {
    sudo pkill -f "showkey" 2>/dev/null
    sudo pkill -f "script.*showkey" 2>/dev/null
    pkill -P $$ 2>/dev/null
    [[ -n $COPROC_PID ]] && kill $COPROC_PID 2>/dev/null
}

while [ $STOP -eq 0 ]; do
    echo "Starting showkey monitoring..."
    
    # Start coprocess
    coproc sudo script -q -c "showkey" /dev/null 2>&1
    
    while [ $STOP -eq 0 ] && kill -0 $COPROC_PID 2>/dev/null; do
        if read -r -t 0.1 line <&${COPROC[0]} 2>/dev/null; then
            echo "$line"

            if [[ $line =~ keycode[[:space:]]+([0-9]+)[[:space:]]+(press|release) ]]; then
                keycode="${BASH_REMATCH[1]}"
                action="${BASH_REMATCH[2]}"
                echo "Keycode: $keycode, Action: $action"

                if [[ $keycode -eq 30 && $action == "press" ]]; then
                    echo "Pressed A!"
                fi
            fi
        fi
    done

    cleanup
    
    if [ $STOP -eq 0 ]; then
        echo "showkey exited, restarting..."
        sleep 1
    fi
done

echo "Exited cleanly."
    fi
done

echo "Exited cleanly."