You are closing your pipe handles in the wrong place. Also if you read with angle brackets, you need the proper line terminator (default \n).

#!/usr/bin/perl

# http://perlmonks.org/?node_id=1173754

use strict;
use warnings;

my ($reader, $writer);
pipe $reader, $writer or die "$! on pipe";
$writer->autoflush;

if( my $pid = fork ) # parent
  {
  close $reader;

  for (1 .. 5)
    {
    my $line = "-- $_ --";
    print "PARENT: Going to transfer line $line\n";
    print $writer "$line\n";

    sleep 1;
    }
  close $writer;

  print "PARENT: closed writer, waiting for child to exit\n";
  1 while wait > 0;
  print "PARENT: exiting\n";
  }
elsif( defined $pid ) # child
  {
  close $writer;

  while( 1 )
    {
    defined( my $line = <$reader> ) or last;
    print "CHILD: Received line $line";
    }

  close $reader;
  print "CHILD: exiting\n";
  exit;
  }
else
  {
  die "$! on fork";
  }
[download]

produces:

PARENT: Going to transfer line -- 1 --
CHILD: Received line -- 1 --
PARENT: Going to transfer line -- 2 --
CHILD: Received line -- 2 --
PARENT: Going to transfer line -- 3 --
CHILD: Received line -- 3 --
PARENT: Going to transfer line -- 4 --
CHILD: Received line -- 4 --
PARENT: Going to transfer line -- 5 --
CHILD: Received line -- 5 --
PARENT: closed writer, waiting for child to exit
CHILD: exiting
PARENT: exiting
[download]