use strict;
use warnings;

use English qw( -no_match_vars ) ;
use Data::Dumper;

sub get_files_in_directory {
    my ( $dir, $filter ) = @_;
    opendir my $DIR, $dir or die "Can't open $dir: $OS_ERROR";
    my @files = grep {/$filter/} readdir($DIR);
    closedir $DIR;
    return @files;
}

# print every file in tmp starting with 'N'
print Dumper( get_files_in_directory( '/tmp', qr/^N/ ) );