#! /bin/sh
# formprog - fill in template form from $1, leave completed form in $2
# TABSTOPS ARE SET AT 4 IN THIS SCRIPT

template="$1"   completed="$2"   errors=/tmp/formprog$$
myname=`basename $0`	# BASENAME OF THIS SCRIPT (NO LEADING PATH)
trap 'rm -f $errors; exit' 0 1 2 15

# READ $template LINE-BY-LINE, WRITE COMPLETED LINES TO $completed:
exec 4<&0	# SAVE ORIGINAL stdin (USUALLY TTY) AS FD 4
while read label text
do
	case "$label" in
	?*:) # FIRST WORD ENDS WITH A COLON; LINE IS OKAY
		case "$text" in
		?*) # SHOW LINE ON SCREEN AND PUT INTO completed FILE:
			echo "$label $text"
			echo "$label $text" 1>&3
			;;
		*)	# FILL IT IN OURSELVES:
			echo -n "$label "
			exec 5<&0	# SAVE template FILE FD; DO NOT CLOSE!
			exec 0<&4	# RESTORE ORIGINAL stdin TO READ ans
			read ans
			exec 0<&5	# RECONNECT template FILE TO stdin
			case "$ans" in
			"") ;;		# EMPTY; DO NOTHING
			*)	echo "$label $ans" 1>&3 ;;
			esac
			;;
		esac
		;;
	*)	echo "$myname: bad $1 line:   '$label $text'" 1>&2; break;;
	esac
done <"$template" 2>$errors 3>"$completed"

if [ -s $errors ]; then
	/bin/cat $errors 1>&2
	echo "$myname: should you remove '$completed' file?" 1>&2
fi