use strict;
use warnings;
use Storable;

package Parent;

sub run {
   my $pipe = shift;

   # der zu sendende String
   my $string  = 'Hello World!';
      $string  = Storable::nfreeze(\$string);
   my $length  = length($string);

   # maximale Bytes die geschrieben werden sollen
   my $maxbyt  = 8;
   my $offset  = 0;
   my $rest    = $length;
   my $sdsz    = $length < $maxbyt ? $length : $maxbyt;

   open my $fh, '>>', $pipe or die $!; 

   while (my $chunk = substr($string, $offset, $sdsz)) {
      syswrite($fh, $chunk, $sdsz) == $sdsz or die;
      $rest -= $maxbyt;
      last unless $rest;
      $offset += $maxbyt;
      $sdsz = $rest if $rest < $maxbyt;
   }   

   close $fh;
}

package Child;

sub run {
   my $pipe   = shift;
   my $rdsz   = 8;
   my $string = (); 

   open my $fh, '<', $pipe or die $!; 

   while (my $byt = read($fh, my $chunk, $rdsz)) {
      die unless $byt == $rdsz;
      $string .= $chunk;
   }   

   close $fh;

   $string = Storable::thaw($string);
   print "\n<$$string>\n";
}

package main;

use POSIX qw/mkfifo/;

my $pipe = int(rand(999999));
mkfifo($pipe, 0600) or die;

if (fork) {
   Parent::run($pipe);
} else {
   Child::run($pipe);
   unlink($pipe);
}