foreach $txtfile (glob("*.TXT")) {
   print $txtfile;
   print "\n";
   open FILE, "$txtfile";
   open NEWFILE, ">$txtfile.tmp";
   while (<FILE>){
      chomp $_;
      if ($. == 1){
         $_ .= " 1.0";     # i.e. $_ = $_ . " 1.0";
      }
      print NEWFILE $_, "\n";
   }
   close FILE;
   close NEWFILE;
}