use strict;
use warnings;

sub usage ()
{
	print STDERR "Usage $0 <unix|linux|dos|mac|apple>\n";
	exit(8);
}

binmode(STDIN);
binmode(STDOUT);

my $eol = "\n";

if ($#ARGV != 0){
	usage();
}
if ($ARGV[0] eq 'linux') {
	$eol = "\n";
} elsif ($ARGV[0] eq 'unix') {
	$eol = "\n";
} elsif ($ARGV[0] eq 'dos') {
	$eol = "\r\n";
} elsif ($ARGV[0] eq 'apple') {
	$eol = "\r";
} elsif ($ARGV[0] eq 'mac') {
	$eol = "\r";
} else {
	usage();
}

while (1) {
	my $ch;     # Character from input

	# Read a character
	my $status = sysread(STDIN, $ch, 1);
	if ($status <= 0){
		last;
	}

	if ($ch eq "\n"){
		syswrite(STDOUT, $eol);
		next;
	}

	if ($ch eq "\r"){
		my $next_ch;     # Check for \r\n
		$status = sysread(STDIN, $next_ch, 1);
		if ($status <= 0){
			syswrite(STDOUT, $eol);
			last;
		}

		# Check for \r\n
		if ($next_ch eq "\n"){
			syswrite(STDOUT, $eol);
			next;
		}

		syswrite(STDOUT, $eol);
		$ch = $next_ch;
	}

	syswrite(STDOUT, $ch);
}