diff --git a/scripts/config.pl b/scripts/config.pl
new file mode 100755
index 000000000..a45253729
--- /dev/null
+++ b/scripts/config.pl
@@ -0,0 +1,142 @@
+#!/usr/bin/env perl
+# 
+# Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org>
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+
+use warnings;
+use strict;
+
+my @arg = @ARGV;
+
+sub load_config($) {
+	my $file = shift;
+	my %config;
+
+	open FILE, "$file" or die "can't open file";
+	while (<FILE>) {
+		chomp;
+		/^CONFIG_(.+)=(.+)/ and do {
+			$config{$1} = $2;
+			next;
+		};
+		/^# CONFIG_(.+) is not set/ and do {
+			$config{$1} = -1;
+			next;
+		};
+		/^#/ and next;
+		/^(.+)$/ and print "WARNING: can't parse line: $1\n";
+	}
+	return \%config;
+}
+
+
+sub config_and($$) {
+	my $cfg1 = shift;
+	my $cfg2 = shift;
+	my %config;
+
+	foreach my $config (keys %$cfg1) {
+		my $val1 = $cfg1->{$config};
+		my $val2 = $cfg2->{$config};
+		$val2 and ($val1 eq $val2) and do {
+			$config{$config} = $val1;
+		};
+	}
+	return \%config;
+}
+
+
+sub config_add($$) {
+	my $cfg1 = shift;
+	my $cfg2 = shift;
+	my %config;
+	
+	for ($cfg1, $cfg2) {
+		my %cfg = %$_;
+		
+		foreach my $config (keys %cfg) {
+			$config{$config} = $cfg{$config};
+		}
+	}
+	return \%config;
+}
+
+sub config_diff($$) {
+	my $cfg1 = shift;
+	my $cfg2 = shift;
+	my %config;
+	
+	foreach my $config (keys %$cfg2) {
+		if (!$cfg1->{$config} or $cfg1->{$config} ne $cfg2->{$config}) {
+			$config{$config} = $cfg2->{$config};
+		}
+	}
+	return \%config
+}
+
+sub config_sub($$) {
+	my $cfg1 = shift;
+	my $cfg2 = shift;
+	my %config = %{$cfg1};
+	
+	foreach my $config (keys %$cfg2) {
+		delete $config{$config};
+	}
+	return \%config;
+}
+
+sub print_cfgline($$) {
+	my $name = shift;
+	my $val = shift;
+	if ($val eq '-1') {
+		print "# CONFIG_$name is not set\n";
+	} else {
+		print "CONFIG_$name=$val\n";
+	}
+}
+
+
+sub dump_config($) {
+	my $cfg = shift;
+	die "argument error in dump_config" unless ($cfg);
+	my %config = %$cfg;
+	foreach my $config (sort keys %config) {
+		print_cfgline($config, $config{$config});
+	}
+}
+
+sub parse_expr($);
+
+sub parse_expr($) {
+	my $pos = shift;
+	my $arg = $arg[$$pos++];
+	
+	die "Parse error" if (!$arg);
+	
+	if ($arg eq '&') {
+		my $arg1 = parse_expr($pos);
+		my $arg2 = parse_expr($pos);
+		return config_and($arg1, $arg2);
+	} elsif ($arg =~ /^\+/) {
+		my $arg1 = parse_expr($pos);
+		my $arg2 = parse_expr($pos);
+		return config_add($arg1, $arg2);
+	} elsif ($arg eq '>') {
+		my $arg1 = parse_expr($pos);
+		my $arg2 = parse_expr($pos);
+		return config_diff($arg1, $arg2);
+	} elsif ($arg eq '-') {
+		my $arg1 = parse_expr($pos);
+		my $arg2 = parse_expr($pos);
+		return config_sub($arg1, $arg2);
+	} else {
+		return load_config($arg);
+	}
+}
+
+my $pos = 0;
+dump_config(parse_expr(\$pos));
+die "Parse error" if ($arg[$pos]);