# this is a test example
my $name = 'doc.txt';
for ( 1 .. 10 ) {
    my $unique = get_unique_filename($name);
    $names{$unique}++;
    print "$unique\n";
}

sub get_unique_filename {
    my $name = shift;
    $name =~ s/(\.[^\.]+)$//;
    my $ext = $1 ? $1 : '';
    my $tries = '';
    my $max_tries = 100;
    while (  not unique_name($name.$tries.$ext) ) {
        $tries++;
        die "Could not make a unique file name $name\n" if $tries > $max_tries;
    }
  return $name.$tries.$ext;
}

# this tests if our name exists in the test hash
# you need to test if the file exists here instead
sub unique_name {
    my $name = shift;
  return defined $names{$name} ? 0 : 1;
  # return -e $name ? 0 : 1;
}