Acho que você pode fazer isso com as variáveis de configuração em /etc/default/grub
. Não esqueça de executar update-grub
após atualizar o arquivo.
GRUB_DEFAULT= 3 #Assuming Windows is the third menu entry
GRUB_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT=0
De acordo com a documentação de cada opção:
'GRUB_DEFAULT'
The default menu entry. This may be a number, in which case it
identifies the Nth entry in the generated menu counted from zero,
or the title of a menu entry, or the special string 'saved'.
Using the title may be useful if you want to set a menu entry as
the default even though there may be a variable number of entries
before it.
For example, if you have:
menuentry 'Example GNU/Linux distribution' --class gnu-linux {
...
}
then you can make this the default using:
GRUB_DEFAULT='Example GNU/Linux distribution'
If you set this to 'saved', then the default menu entry will be
that saved by 'GRUB_SAVEDEFAULT', 'grub-set-default', or
'grub-reboot'.
The default is '0'.
'GRUB_TIMEOUT'
Boot the default entry this many seconds after the menu is
displayed, unless a key is pressed. The default is '5'. Set to
'0' to boot immediately without displaying the menu, or to '-1' to
wait indefinitely.
'GRUB_HIDDEN_TIMEOUT'
Wait this many seconds for a key to be pressed before displaying
the menu. If no key is pressed during that time, boot
immediately. Unset by default.