ask

#!/usr/bin/env bash
#
# Ask (https://djm.me/ask)

# This is a general-purpose function to ask yes/no questions in Bash, either
# with or without a default answer. It keeps repeating the question until it
# gets a valid answer.

# color variables
yellow=$(tput setaf 3)
reset=$(tput sgr0)

function ask() {
  local prompt default reply

  if [ "${2:-}" = "Y" ]; then
    prompt="Y/n"
    default=Y
  elif [ "${2:-}" = "N" ]; then
    prompt="y/N"
    default=N
  else
    prompt="y/n"
    default=
  fi

  while true; do

    # Ask the question (not using "read -p" as it uses stderr not stdout)
    echo -ne "${yellow}$1 [$prompt] ${reset}"

    # Read the answer (use /dev/tty in case stdin is redirected from somewhere else)
    read -r reply </dev/tty

    # Default?
    if [ -z "$reply" ]; then
      reply=$default
    fi

    # Check if the reply is valid
    case "$reply" in
    Y* | y*) return 0 ;;
    N* | n*) return 1 ;;
    esac

  done
}