Perl script to change file extensions

#!/usr/bin/perl -w  print("File extension that you want to change: "); chomp($badex = <STDIN>);  print("File extension that you want added: "); chomp($goodex = <STDIN>);  foreach $file (<*$badex>){     @fields = split(/$badex/,$file);     $goodfile = ("$fields[0]" . "$goodex");      rename("$file","$goodfile"); }