use warnings;
use strict;

scandir( $ARGV[0] ); ## where to look from CLI

sub scandir {
    my ($file) = @_;
    if ( -d $file ) {
	print $file,$/;  ## print directory name
        opendir my $dh, $file or die "can't open directory: $!";
        while ( readdir($dh) ) {
            chomp;
            next if $_ eq '.' or $_ eq '..';
            print "\t", $_, $/ if /\.pl$/;   ## print *.pl files
            scandir("$file/$_");             ## check sub-directory...
        }
    }
}