without using any outside module

as a starting point, you might want to take a look at the following very basic subroutine which recursively traverses the subdirectory tree:

sub traverse_dir {
    my $dir = shift;
    my @entries = glob "$dir/*";
    for my $entry (@entries) {
        if (-f $entry) {
            print "$entry:", -s $entry, "\n";
        } elsif (-d $entry) {
            traverse_dir($entry);
        } else
            # perhaps do something for entries which are neither files
+ nor subdirectories, if that sort of thing exists
        }
    }
}
traverse_dir ".";
[download]

Also note that I have used the -d, -f and -s file test operators for simplicity, but in a real program, I would probably use the stat (and possibly lstat) built-in function instead. Also, you might want to replace the glob function call by a opendir and readdir combination, together with appropriate calls to grep to get rid of entries such as . and .. (which are skipped by glob).

Update: see To glob or not to glob for a discussion of glob and some of its advantages and disadvantages.

Are core modules permissible?

File::Find can be used to traverse a portion of a filesystem and tally things up. It's a rather inefficient solution if you want an entire volume's usage. The utilitydf would be better for information on an entire volume, and can be wrapped in a Perl call. And if you need to tally usage of a portion of a volume du would be useful. But if du and df are off the table, File::Find along with stat are good starting points.

The File::Find module has been bundled with Perl since Perl 5 began. If it is not allowed as part of the solution, then push back on that requirement, because the same logic would also prevent using strict and warnings.

"...without..."

Still worth to read, especially what merlyn wrote 16 years ago.

You may cheat (AKA code reuse) from File::Find.

Best regards, Karl

There is nothing wrong with cross-posting questions, but it is considered proper to inform your reader to avoid duplication of work on various parts of the Internet.

ppt du

disk usage

There are very good reasons why you should use an existing, battle-tested module instead of trying to "roll your own." The CPAN library contains several tested ways to do this, and if you simply leverage one of them (without bothering to peek under the hood), both you and everyone who will follow in your footsteps will know that it works.

And yet you list none of those reasons; and of course, everything on cpan always works, all the time. Yes Sundail; I recognise you even incognito.

---

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Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority". The enemy of (IT) success is complexity.

In the absence of evidence, opinion is indistinguishable from prejudice. Suck that fhit