A quick bash common function that can be used to ask multiple choice questions and ensure an answer.

general_request.sh

#!/bin/bash

function ask_multi_choice() {
  local QUESTION=$1

  while [ -z "$CHOICE" ]; do
    echo
    for S in ${!POSSIBLE_ANSWERS[*]}; do
      echo "  ${S}) ${POSSIBLE_ANSWERS[$S]}"
    done

    echo
    read -r -p "${QUESTION}: "

    if [ -n "$REPLY" ]; then
      CHOICE="${POSSIBLE_ANSWERS[$REPLY]}"
    fi
  done

  export ANSWER="${CHOICE}"
}


declare -A POSSIBLE_ANSWERS
POSSIBLE_ANSWERS["1"]="eth0"
POSSIBLE_ANSWERS["2"]="at0"
POSSIBLE_ANSWERS["3"]="wlan0"

ask_multi_choice "Pick an interface"
echo $ANSWER