Casing arrow keys in bash

Question

Is it possible to case arrow keys in a bash script to run a certain set of commands if the up/left arrow keys are pressed, and a certain set if the down/right arrow keys are

Answer 1

As mentioned before, the cursor keys generate three bytes - and keys like home/end even generate four! A solution I saw somewhere was to let the initial one-char read() follow three subsequent one-char reads with a very short timeout. Most common key sequences can be shown like this f.e.:

#!/bin/bash
for term in vt100 linux screen xterm
  { echo "$term:"
    infocmp -L1 $term|egrep 'key_(left|right|up|down|home|end)'
  }

Also, /etc/inputrc contains some of these with readline mappings.. So, answering original question, here's a snip from that bash menu i'm just hacking away at:

while read -sN1 key # 1 char (not delimiter), silent
do
  # catch multi-char special key sequences
  read -sN1 -t 0.0001 k1
  read -sN1 -t 0.0001 k2
  read -sN1 -t 0.0001 k3
  key+=${k1}${k2}${k3}

  case "$key" in
    i|j|$'\e[A'|$'\e0A'|$'\e[D'|$'\e0D')  # cursor up, left: previous item
      ((cur > 1)) && ((cur--));;

    k|l|$'\e[B'|$'\e0B'|$'\e[C'|$'\e0C')  # cursor down, right: next item
      ((cur < $#-1)) && ((cur++));;

    $'\e[1~'|$'\e0H'|$'\e[H')  # home: first item
      cur=0;;

    $'\e[4~'|$'\e0F'|$'\e[F')  # end: last item
      ((cur=$#-1));;

    ' ')  # space: mark/unmark item
      array_contains ${cur} "${sel[@]}" && \
      sel=($(array_remove $cur "${sel[@]}")) \
      || sel+=($cur);;

    q|'') # q, carriage return: quit
      echo "${sel[@]}" && return;;
  esac                  

  draw_menu $cur "${#sel[@]}" "${sel[@]}" "$@" >/dev/tty
  cursor_up $#
done