use strict;
use warnings;

use IO::File;

my $pipe = "/tmp/mypipe";
system('mkfifo', '--', $pipe) if !-p $pipe;

open(my $to_child, '|-', "cat > ".text_to_shell_lit($pipe))
   or die "Can't open create process 1: $!";
$to_child->autoflush(1);

open(my $fr_child, '|-', "cat < ".text_to_shell_lit($pipe))
   or die "Can't open create process 2: $!";

my $input = '12345678901234567890123456789012345678901234567890';

print($to_child $input);
close($to_child);

while (<$fr_child>) {
    print;
}