#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11141789
use warnings;

my $filename = 'tmp.11141789';

open my $fh, '>>', $filename or die "$! opening $filename";
printf "1) fileno = %s\n", $fh->fileno // 'undefined';
close $fh or die "$! closing $filename";
printf "2) fileno = %s\n", $fh->fileno // 'undefined';
close $fh or die "$! closing $filename";
printf "3) fileno = %s\n", $fh->fileno // 'undefined';
close $fh or die "$! closing $filename";

##</code><code>##

1) fileno = 3
2) fileno = undefined
Bad file descriptor closing tmp.11141789 at ./pm11141789.pl line 12.