Save the named variables from the environment to the environment block file. See Environment block.
The --file option overrides the default location of the environment block.
This command will operate successfully even when environment variable
check_signatures is set to
(see check_signatures), since it writes to disk and does not alter
the behavior of GRUB based on any contents of disk that have been
read. It is possible to modify a digitally signed environment block
file from within GRUB using this command, such that its signature will
no longer be valid on subsequent boots. Care should be taken in such
advanced configurations to avoid rendering the system
unbootable. See Using digital signatures, for more information.