#!/usr/bin/perl

use strict;
use warnings;

print "I'm the master ($$)\n";

my %pids;
my $children = 2;

for my $x (1 .. $children) {
    my ($fh, $pid);
    my $tries = 6;
    do {$pid = open $fh, "|-";
        unless (defined $pid) {
            warn "fork: $!\n";
            die "bailing out" unless $tries--; 
            sleep 5;
        }
    } until defined $pid;
    if ($pid) {
        print "I'm master ($$) of child ($pid)\n";
        $pids {$pid} = $fh;
    }
    else {
        printf "I'm a child ($$) of master (%d)\n", getppid;
        while (<>) {
            chomp;
            printf "Child ($$) received: [%s]\n", $_;
        }
        print "Child ($$) exiting\n";
        exit;
    }
}
my $count = 0;
while (my ($pid, $fh) = each %pids) {
    my $data = sprintf "[[%02d]]", ++$count;
    printf "Sending data %s to child (%d)\n", $data, $pid;
    print $fh $data, "\n";
}
while (my ($pid, $fh) = each %pids) {
    printf "Closing handle to child (%d)\n", $pid;
    close $fh or warn "Failed to close handle for child ($pid)\n";
}
    
print "Last line\n";

__END__
I'm the master (19054)
I'm a child (19055) of master (19054)
I'm master (19054) of child (19055)
I'm a child (19056) of master (19054)
I'm master (19054) of child (19056)
Sending data [[01]] to child (19056)
Sending data [[02]] to child (19055)
Closing handle to child (19056)
Child (19056) received: [[[01]]]
Child (19056) exiting
Closing handle to child (19055)
Child (19055) received: [[[02]]]
Child (19055) exiting
Last line
[download]