CmdID / Commands
grub-set-default
Set the default boot entry for GRUB. tldr-pages
On Linux
Set the default boot entry to an entry number, name, or identifier
sudo grub-set-default entry_numberIdentify
Set the default boot entry to an entry number, name, or identifier for an alternative boot directory
sudo grub-set-default --boot-directory /path/to/boot_directory entry_numberIdentify