Added a check for config-file.

scripts/mysqld_multi.sh

@@ -87,7 +87,7 @@ sub main
   {
     $flag_exit= 1;
   }
-  if (!($opt_config_file =~ m/\//))
+  if (defined($opt_config_file) && !($opt_config_file =~ m/\//))
   {
     # No path. Use current working directory
     $opt_config_file= "./" . $opt_config_file;