#!/usr/bin/perl
use strict;
use warnings;

use vars qw( @data $prev $IN @sorted $OUT);

$prev = 0;
open($IN, '<', 'data');
while (<$IN>) {
    chomp;
    my $next = tell($IN);
    my ($key) = /^([^\s]*)/;
    push(@data, [ $key, $prev, $next - $prev ]);
    $prev = $next;
}
close($IN);

@sorted = sort( { $a->[0] cmp $b->[0] } @data);

open($IN, '<', 'data');
open($OUT, '>', 'sorteddata');
for (@sorted) {
    seek($IN, $_->[1], 0);
    sysread($IN, my $line, $_->[2]);
    print $OUT $line;
}
close($IN);
close($OUT);