--- a/configure.sh
+++ b/configure.sh
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh
 #
 # configure.sh	Generates interactively a config.h from config.in
 #
@@ -25,20 +25,9 @@
 #		Foundation;  either  version 2 of the License, or  (at
 #		your option) any later version.
 #
-#
-# Make sure we're really running bash.
-#
-# I would really have preferred to write this script in a language with
-# better string handling, but alas, bash is the only scripting language
-# that I can be reasonable sure everybody has on their Linux machine.
-#
-
 CONFIG=config.h
 MAKECONFIG=config.make
 
-
-[ -z "$BASH" ] && { echo "configure.sh requires bash" 1>&2; exit 1; }
-
 cat <<EOF
 
 ######################################################
@@ -48,26 +37,24 @@
 EOF
 
 # Disable filename globbing once and for all.
-# Enable function cacheing.
-set -f -h
+set -f
 
 # set up reading of config file
 if [ "$#" != "1" ] || [ ! -f "$1" ]; then
 	echo "usage: $0 configfile" 1>&2
 	exit 1
 fi
-exec 7<$1
-config_fd_redir='<&7'
+exec 7<"$1"
 
 #
 # readln reads a line into $ans.
 #
 #	readln prompt default
 #
-function readln()
+readln()
 {
-  echo -n "$1"
-  IFS='@' read ans || exit 1
+  printf '%s' "$1"
+  IFS='@' read -r ans || exit 1
   [ -z "$ans" ] && ans=$2
 }
 
@@ -75,21 +62,21 @@
 #
 #	bool tail
 #
-function bool()
+bool()
 {
-  # Slimier hack to get bash to rescan a line.
+  # Re-scan the line so shell quoting from config.in is preserved.
   eval "set -- $1"
   ans=""
-  while [ "$ans" != "y" -a "$ans" != "n" ]
+  while [ "$ans" != "y" ] && [ "$ans" != "n" ]
   do
 	readln "$1 ($2) [$3] " "$3"
   done
   if [ "$ans" = "y" ]; then
-	echo "#define $2 1" >>${CONFIG}
-	echo "$2=1" >>${MAKECONFIG}
+	echo "#define $2 1" >>"${CONFIG}"
+	echo "$2=1" >>"${MAKECONFIG}"
     else
-	echo "#define $2 0" >>${CONFIG}
-	echo "# $2=0" >> ${MAKECONFIG}
+	echo "#define $2 0" >>"${CONFIG}"
+	echo "# $2=0" >>"${MAKECONFIG}"
   fi
   raw_input_line="bool '$1' $2 $ans"
   eval "$2=$ans"
@@ -99,16 +86,42 @@
 #
 #	int tail
 #
-function int()
+is_integer()
 {
-  # Slimier hack to get bash to rescan a line.
+  case $1 in
+    ''|*[!0123456789+-]*|*[-+]*[-+]*)
+      return 1
+      ;;
+    [+-])
+      return 1
+      ;;
+  esac
+
+  case $1 in
+    [+-]*)
+      set -- "${1#?}"
+      ;;
+  esac
+
+  case $1 in
+    ''|*[!0123456789]*)
+      return 1
+      ;;
+  esac
+
+  return 0
+}
+
+int()
+{
+  # Re-scan the line so shell quoting from config.in is preserved.
   eval "set -- $1"
   ans="x"
-  while [ $[$ans+0] != "$ans" ];
+  while ! is_integer "$ans"
   do
 	readln "$1 ($2) [$3] " "$3"
   done
-  echo "#define $2 ($ans)" >>${CONFIG}
+  echo "#define $2 ($ans)" >>"${CONFIG}"
   raw_input_line="int '$1' $2 $ans"
   eval "$2=$ans"
 }
@@ -123,10 +136,10 @@
   stack=''
   branch='t'
 
-  while IFS='@' eval read raw_input_line ${config_fd_redir}
+  while IFS='@' read -r raw_input_line <&7
   do
-	# Slimy hack to get bash to rescan a line.
-	read cmd rest <<-END_OF_COMMAND
+	# Re-scan the line so shell quoting from config.in is preserved.
+	IFS=' ' read -r cmd rest <<-END_OF_COMMAND
 		$raw_input_line
 	END_OF_COMMAND
 
@@ -135,18 +148,18 @@
 			echo "$raw_input_line"
 			# echo "# $rest" >>$CONFIG
 			if [ "$prevcmd" != "*" ]; then
-				echo >>${CONFIG}
-				echo "/* $rest" >>${CONFIG}
+				echo >>"${CONFIG}"
+				echo "/* $rest" >>"${CONFIG}"
 			else
-				echo " * $rest" >>${CONFIG}
+				echo " * $rest" >>"${CONFIG}"
 			fi
 			prevcmd="*"
 		fi
 	else
-		[ "$prevcmd" = "*" ] && echo " */" >>${CONFIG}
+		[ "$prevcmd" = "*" ] && echo " */" >>"${CONFIG}"
 		prevcmd=""
 		case "$cmd" in
-		=)	[ "$branch" = "t" ] && echo "$rest" >>${CONFIG};;
+		=)	[ "$branch" = "t" ] && echo "$rest" >>"${CONFIG}";;
 		:)	[ "$branch" = "t" ] && echo "$raw_input_line" ;;
 		int)	[ "$branch" = "t" ] && int "$rest" ;;
 		bool)	[ "$branch" = "t" ] && bool "$rest" ;;
@@ -160,12 +173,12 @@
 		else)	if [ "$branch" = "t" ]; then
 				branch=f
 			else
-				read branch rest <<-END_OF_STACK
-					$stack
-				END_OF_STACK
-			fi ;;
+					IFS=' ' read -r branch rest <<-END_OF_STACK
+						$stack
+					END_OF_STACK
+				fi ;;
 		fi)	[ -z "$stack" ] && echo "Error!  Extra fi." 1>&2
-			read branch stack <<-END_OF_STACK
+			IFS=' ' read -r branch stack <<-END_OF_STACK
 				$stack
 			END_OF_STACK
 			;;
@@ -173,7 +186,7 @@
 	fi
 	echo "$raw_input_line" >>config.new
   done
-  [ "$prevcmd" = "*" ] && echo " */" >>${CONFIG}
+  [ "$prevcmd" = "*" ] && echo " */" >>"${CONFIG}"
 
   [ -z "$stack" ] || echo "Error!  Unterminated if." 1>&2