Duas abordagens para detecção de setas em Shell Script

arrow_key_detect_approaches.sh

#!/bin/bash
## solution1: $ sh arrow_key.sh
## solution2: $ sh arrow_key.sh 2 [-v]
: '
 a  d  e  f  m  o  u  ASCII
61 64 65 66 6D 6F 75  HEX

HEX           ASCII
0a            \n or \s
1b 5b 41      \033[A  # Up arrow
1b 5b 42      \033[B  # Down arrow
1b 5b 43      \033[C  # Right arrow
1b 5b 44      \033[D  # Left arrow
1b 5b 32 7e   \033[2~ # insert key
1b 5b 33 7e   \033[3~ # delete key
1b 5b 35 7e   \033[5~ # page up key
1b 5b 36 7e   \033[6~ # page down key
 |  |  |
 |  |  +------ ASCII A, B, C, D, 2, 3, 5 and 6
 |  +--------- ASCII [
 +------------ ASCII ESC
'


## --------------------------------------------------------- ##
bind_arrow_up() { printf "\033[41m Up \033[0m\n"; }
bind_arrow_down() { printf "\033[45m Down \033[0m\n"; }
bind_arrow_right() { printf "\033[43m Right \033[0m\n"; }
bind_arrow_left() { printf "\033[44m Left \033[0m\n"; }

bind_esc() { printf "\033[32m Esc \033[0m\n"; }
bind_blank() { printf "\033[35m Enter or Space \033[0m\n"; }
bind_insert() { printf "\033[32m insert \033[0m\n"; } #-
bind_delete() { printf "\033[31m delete \033[0m\n"; } #-
## --------------------------------------------------------- ##


## (c) http://github.com/micalevisk
## estratégia: um-dois
## quantidade de leituras: 3
## problemas: não entende setas pressionadas, apenas clicadas
function solution1 {

  while read -rsn1 ui ##§
  do

    case "$ui" in
      $'\x1b') ## Handle ESC sequence.
        read -rsn2 -t 0.1 key ##§
        # od -tx1 <<< "$key"
        [ "${key:0:1}" != '[' ] && bind_esc || {
          case "${key:1:1}" in
            'A') bind_arrow_up ;;
            'B') bind_arrow_down ;;
            'C') bind_arrow_right ;;
            'D') bind_arrow_left ;;
            '2') bind_insert ;;
            '3') bind_delete ;;
          esac
        }
        # Flush "stdin" with 0.1  sec timeout.
        read -rsn5 -t 0.1 ;; ##§

      $'') bind_blank ;;

      *) #printf "other... quiting\n"; break;;
        od -tx1 <<< "$ui"; break;;
    esac

  done

}

## (c) https://unix.stackexchange.com/questions/179191
## estratégia: um-um-um
## quantidade de leituras: 4
## problemas: delay perceptível; não entende setas pressionadas, apenas clicadas, nem cliques rápidos
function solution2 {

  while read -rsn1 ui ##§
  do
    printf "~~~~~~~~~~~~~~~~~1\n" 1>&3
    hexdump -C <<< "$ui" 1>&3

    case "$ui" in
      $'\x1b') ## Handle ESC sequence.
        ## Flush read. We account for sequences for Fx keys as well. 6 should suffice far more then enough.
        read -rsn1 -t 0.1 tmp ##§
        printf "_________________2\n" 1>&3
        hexdump -C <<< "$tmp" 1>&3

        if [ "$tmp" == "[" ]
        then
          read -rsn1 -t 0.1 tmp ##§
          printf "_________________3\n" 1>&3
          hexdump -C <<< "$tmp" 1>&3

          case "$tmp" in
            'A') bind_arrow_up ;;
            'B') bind_arrow_down ;;
            'C') bind_arrow_right ;;
            'D') bind_arrow_left ;;
            '2') bind_insert ;;
            '3') bind_delete ;;
          esac
        elif [ -z "$tmp" ]
        then
          bind_esc
        fi

        # Flush "stdin" with 0.1  sec timeout.
        read -rsn5 -t 0.1 ;; ##§

      $'') bind_blank ;;

      ## Other one byte (char) cases. Here only quit.
      *) printf "other... quiting\n"; break;;
    esac
  done

}



exec 3>/dev/null # não verboso
[ "$2" == "-v" ] && exec 3>&2 # verboso (para debug)

printf "Press an arrow key...\n\n"
[ "$1" == 2 ] && solution2 || solution1