#!/usr/bin/env perl 
use strict;
use warnings;
use utf8;

use strict;
use warnings;
use LWP::UserAgent;

# Modify these three variables only to suit
my $url        = 'http://www.gutenberg.org/ebooks/1533.txt.utf-8'; # MacBeth
my $wantlines  = 30; # Retrieve this number of lines
my $bytes      = 256; # Chunk size to download

my $firstndata;
my $linecount  = 0;
my $chunkcount = 0;

sub add_chunk {
    my ($chunk, $res, $proto) = @_;
    $firstndata .= $chunk;
    $linecount += () = $chunk =~ /\n/g;
    $chunkcount++;
    die if $linecount >= $wantlines;
}

my $ua = LWP::UserAgent->new;
my $res = $ua->get ($url, ':content_cb' => \&add_chunk, ':read_size_hint' => $bytes);

print "Retrieved $linecount lines in $chunkcount chunks from $url:\n\n$firstndata\n";