#!/usr/local/bin/perl

use strict;
use warnings;

use IO::Handle;
use IO::Select;

my $handle;
my $pid;
if (!defined($pid = open($handle, "|-"))) {
    die "Fork failed: ".$!;
}
elsif ($pid == 0) {
    # Child
    sleep(5);
    exit 0;
}
else {
    # Parent
    $handle->autoflush(1);
    my $selector = IO::Select->new($handle);
    my $i = 0;
    do {
        if ($selector->can_write(0)) {
            print $handle "ABC\n";
            print "PIPE write ".++$i."\n";
        }
        else {
            print "PIPE cannot write\n";
        }
    } while (1);
}
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