#!/usr/bin/perl

=head1 NAME

not - print lines that are present in one file but not another

=head1 SYNOPSIS

not file

not [file|-] [file|-] ...

=head1 DESCRIPTION

B<not> reads the specified files and prints out the lines that are present
in the first but not in subsequent files. Use "-" to make it read a file
from standard input. If only one file is specified, B<not> first reads
standard input, and compares it with the specified file.

=head1 AUTHOR

Copyright 2006 by Joey Hess <joey@kitenet.net>

Licensed under the GNU GPL.

=cut

use warnings;
use strict;

if (@ARGV == 0) {
	die "usage: not [file|-] [file|-] ...\n";
}

if (@ARGV == 1) {
	unshift @ARGV, "-";
}

my $first=shift;

my %seen;
foreach my $fn (@ARGV) {
	open (IN, $fn) || die "and: read $fn: $!\n";
	while (<IN>) {
		chomp;
		$seen{$_}++;
	}
	close IN;
}


open (IN, $first) || die "and: read $first: $!\n";
while (<IN>) {
	chomp;
	print "$_\n" if ! $seen{$_};
}
close IN;