Here is a nice example from the book Higher-Order Perl by Mark Jason Dominus

This example is for win32, but it is easily changable:

    use strict;
    use warnings;
    
    use Time::HiRes qw(gettimeofday tv_interval);

    my $start_time = [gettimeofday];

    my $inp_dir = 'c:\temp\Tmp_User';

    my ( $startdir ) = @ARGV;

    $startdir = $inp_dir;

    ( defined $startdir ) || usage();

    walk_path( \&is_req_file, $startdir );
    my $elapsed = tv_interval($start_time);
    $elapsed = sprintf "%.04f", $elapsed;
    print "\n...Elapsed   is $elapsed sec\n";

    1;

    sub is_req_file {
    
        my ($filn) = @_; 

        print "$filn\n"; 

        return 1;
    }
    sub walk_path {
        my ( $filefunc, $startdir ) = @_;
        my $dos_cmd = "dir $startdir /b /S /A:-D";
        map {
            $filefunc->($_)
        } ( split /\n/, qx{$dos_cmd} );
        return;
    }
[download]

The advantage is, that it runs really fast on windows.

The missing sub usage is left as an exercise.