update-grub
gera o arquivo grub.cfg
do grub, que o grub lê na inicialização, com base na configuração do grub em /etc/default/grub
. (O Grub não lê /etc/default/grub
na inicialização).
Trecho de Ubuntu Wiki, Grub2 :
The main Grub 2 configuration file, normally located in the
/boot/grub
folder, is grub.cfg. It is the product of various scripts and should not normally be edited directly.
grub.cfg
is overwritten by certain Grub 2 package updates, whenever a kernel is added or removed, or when the user runsupdate-grub