If used in the first section of a menu file, disable all interactive
editing control (menu entry editor and command-line) and entries
protected by the command lock. If the password passwd is
entered, it loads the new-config-file as a new config file and
restarts the GRUB Stage 2, if new-config-file is
specified. Otherwise, GRUB will just unlock the privileged instructions.
You can also use this command in the script section, in which case it
will ask for the password, before continuing. The option
--md5 tells GRUB that passwd is encrypted with
md5crypt (see md5crypt).