use warnings;
use strict;
sub ph {
    print `handle -nobanner -u -p $$`;      # shows handle id (hex), type (file), mode (rw-), and filename
    print `handle -nobanner -u blah`;       # shows exe, pid, type, owner, id (hex), filename
    print `handle -nobanner -s -p $$`;      # shows summary of all the different handle types open by that process
    print 'HIT ENTER'; <STDIN>;
}
local $\ = $/;
print $$;
ph();
open my $wr, '>', 'blah';
ph();
open my $rd, '<', 'blah';
ph();
open my $wrnul, '>', 'NUL';
open my $rdnul, '<', 'NUL';
close $wr;
close $rd;
ph();