$dir= shift || '.';

opendir DIR, $dir or die "Can't open directory $dir: $!\n";

while ($file= readdir DIR) {
    next if $file=~/^\./;
        open (FH, ">", "$file") or die "Can't open file $file: $!\n";
        my @file_lines=<FH>;

##</code><code>##

     open (FH, "$dir/$file") ...