# launcher.pl

use strict;
use warnings;

use Win32;
use Win32::Process;

sub ErrorReport{
   return Win32::FormatMessage( Win32::GetLastError() );
}

my $detached = $ARGV[0];

unlink('foo');

Win32::Process::Create(
   my $ProcessObj,
   "c:\\progs\\perl5100\\bin\\perl.exe",
   q{perl.exe -le"sleep 5; open $fh, '>foo' or die $!; print 'done'"},
   0,
   NORMAL_PRIORITY_CLASS | ($detached ? DETACHED_PROCESS : 0),
   '.',
)
   or die ErrorReport();

##</code><code>##

>perl -e"print `perl launcher.pl 0`" & dir /b foo
[waits 5 seconds]
done
foo

>perl -e"print `perl launcher.pl 1`" & dir /b foo
[returns immediately]
File Not Found

>perl -e"sleep 5" & dir /b foo
foo