ASK - asks Yes/no question (with signal handling)

ask.sh

#! /bin/sh

#  ASK - asks Yes/no question (with signal handling)
#  Copyright (C) 2011 Matous J. Fialka, <http://mjf.cz/>
#  Released under the Terms of The MIT License


signal_handler()
{
	printf -- 'Interrupted.'

	trap - 2
	kill -2 $$

	exit 130
}

trap signal_handler 1 2 3 13 15


ask=Yes/no

if [ $# -gt 0 ]
then
	case $1 in

	-h|-help)
		printf -- 'ask [-hn] text\n'
		exit 0
		;;

	-n|-no)
		ask=No/yes
		shift
		;;

	--)
		shift
		;;
	esac
fi


while :
do
	printf -- '%s' "$*"

	if [ $# -gt 0 ]
	then
		printf -- '  ('
	fi

	case $ask in

	Yes/no|'')
		printf -- Yes/no
		;;

	No/yes)
		printf -- No/yes
		;;
	esac

	if [ $# -gt 0 ]
	then
		printf -- ')'
	else
		printf -- '?'
	fi

	printf -- '  '

	read -s -n 1 answer

	case "$answer" in

	'')
		case $ask in

		Yes/no|'')
			printf -- 'Certainly.\n'
			exit 0
			;;

		No/yes)
			printf -- 'Certainly not.\n'
			exit 1
			;;
		esac
		;;

	y|Y)
		printf -- 'Yes.\n'
		exit 0
		;;

	n|N)
		printf -- 'No.\n'
		exit 1
		;;

	*)
		printf -- 'Wrong answer.\n'
		;;
	esac
done