Grub2 – Community Ubuntu Documentation says the following:
Saving an OS can be achieved by running sudo grub-set-default if
DEFAULT=saved is set in /etc/default/grub. It may also be saved if
GRUB_SAVEDEFAULT=true is also set in /etc/default/grub. In this case,
the default OS remains until a new OS is manually selected from the
GRUB 2 menu or the grub-set-default command is executed.
I put the lines
/etc/default/grub, and ran
sudo grub-set-default. Here is the output:
$ sudo grub-set-default
entry not specified.
Usage: grub-set-default [OPTION] entry
Set the default boot entry for GRUB.
-h, --help print this message and exit
-v, --version print the version information and exit
--boot-directory=DIR expect GRUB images under the directory DIR/grub
instead of the /boot/grub directory
ENTRY is a number or a menu item title.
Report bugs to <firstname.lastname@example.org>.
Am I not following the documentation correctly? What's the correct way to do this?