https://www.facebook.com/groups/RasPiCommunity/permalink/117

#!/bin/bash
# betlog - 2019-04-27
# modified from : https://stackoverflow.com/questions/10679188/casing-arrow-keys-in-bash
MIN=00
MAX=99
#-------
count=00

escape_char=$(printf "\u1b")
while :; do
    read -rsn1 mode # get 1 character
    if [[ $mode == $escape_char ]]; then
        read -rsn2 mode # read 2 more chars
    fi
    case $mode in
        'q') echo QUITTING ; exit ;;
        '[A') echo UP ;;
        '[B') echo DN ;;
        '[D')  #leftarrow
            if [[ $count-1 -lt $MIN ]]; then
                echo -ne "NOPE \a\n"
            else
                let count=count-1
                echo $(printf %02d $count)
            fi
            ;;
        '[C') #rightarrow
            if [[ $count -gt $MAX-1 ]]; then
                echo -ne "NOPE \a\n"
            else
                let count=count+1
                echo $(printf %02d $count)
            fi
            ;;
        *) >&2 echo 'ERR bad input'; return ;;
    esac
done