#!/usr/bin/perl
$|++;

my $pid = fork();    

unless($pid) {
  while(1..) {
        prozess_bei_den_eltern();
  }
  CORE::exit;
}

sub prozess_bei_den_eltern {
    # hier sind wir wieder bei den Eltern
}

#!/usr/bin/perl
$|++;

use Tk;
my $pid = fork();    

unless($pid) {
    while(1..5) {
        sleep(1);
        prozess_bei_den_eltern("$_");
    }
    CORE::exit;
}

my $window = MainWindow->new();

$window->Label(-text=>'')->pack();

sub prozess_bei_den_eltern {
    $window->configure(-text => $_[0]);    
}

MainLoop;

#!/usr/bin/perl
$|++;

my $pid = fork();

pipe(READER, WRITER);

unless($pid) {
   while(1..) {
       print READER "Text vom Kind";
       sleep(1);
   }
   CORE::exit;
}
for(<READER>) {
  print "Das Kind schreibt: $_\n";
}
close(READER);

# !!!was hier folgt wird nichtmehr ausgeführt !!!

#!/usr/bin/perl
$|++;

use strict;
use warnings;

use IO::Pipe;
use IO::Select;

my $pipe = IO::Pipe->new;

my $pid = fork();

unless($pid) {
    $pipe->writer;
    $pipe->autoflush(1);

      for (1..2) {
          $pipe->print("Text vom Kind\n");
          sleep(2);
      }

} else {
    $pipe->reader;
    $pipe->autoflush(1);

    my $select = IO::Select->new($pipe);

    while(1) {
        if(my @handles = $select->can_read(0)) {
            foreach (@handles) {
                my $line = $_->readline;
                print "Das Kind schreibt: $line\n";
            }
        }
        print "Papa arbeitet.\n";
        sleep(1);
    }
}