#!/usr/local/bin/perl

open(FILE_LIST, "ls *.txt|") || die "couldn't open file list: $!";

while(<FILE_LIST>) {
   $old_name = $_;
   chomp($old_name);
   ($name, $extension) = split(/\./, $old_name);
   $new_name = join('', $name, ".tmp"); 
   $command = join(' ', "cp", $old_name, $new_name);
   system $command;
}

close(FILE_LIST);