$ cat input.txt 
module abc(
rist_top_tck,
rist_top_tdi,
rist_top_tdo,
$ ./double.pl input.txt
module abc(
.rist_top_tck(rist_top_tck),
.rist_top_tdi(rist_top_tdi),
.rist_top_tdo(rist_top_tdo));
$