#!/usr/bin/perl -w
my $CMD = 'cat';
use IO::Handle;
use IPC::Open3 qw( open3 );
use strict;

my $pid;
if(  $^W =~ /mswin32/i  ) {
    unless(  @ARGV  &&  $ARGV[0] =~ /^-child$/i  ) {
        $pid= system( 1, qq("$^X" "$0" -child) )
          or  die "system() failed: $!\n";
    } else {
        shift @ARGV;
        $pid= 0;
    }
} else {
    $pid = fork();
    if ( !defined($pid) ) {
        die( "$$: Fork failed: $!\n" );
    }
}

# parent
if ( $pid ) {
#...