sub eval_cmd {

   my $key = shift;

   die "no such command: $key!" unless exists $cmd_template{$key};

   my $cmd = $cmd_template{$key};
   no strict "vars";
   for my $var (@all_my_vars) {
      $cmd =~ s/\$var/$$var/g if defined $$var;
   }
   use strict "vars";
   return $cmd;
}