opendir(DIR,$destinationdirectory) or die "Could not open $destinationdirectory because $!\n";

foreach (my $zips = readdir(DIR)){
     ($txt = $zips) =~ s/\.log$/.txt/i;

      unless(rename($zips, $txt)){
        warn "could not rename $zips to $txt because $!\n";
        next;
      }
}