On testing this again on Ubuntu 18.10 dev with grub-pc 2.02-2ubuntu13 and this time by not setting GRUB_HIDDEN_TIMEOUT at all, setting GRUB_TIMEOUT to 0.0 and then testing with GRUB_TIMEOUT_STYLE being set to menu (while keeping shift pressed at booting), hidden (while keeping ESC pressed at booting) and coutdown (while keeping ESC pressed at booting) I'm still seing the behavior from the startpost.
> ‘GRUB_TIMEOUT_STYLE’
>
> If this option is unset or set to ‘menu’, then GRUB will display the menu and then wait for the timeout set by ‘GRUB_TIMEOUT’ to expire before booting the default entry. Pressing a key interrupts the timeout.
>
> If this option is set to ‘countdown’ or ‘hidden’, then, before displaying the menu, GRUB will wait for the timeout set by ‘GRUB_TIMEOUT’ to expire. If ESC is pressed during that time, it will display the menu and wait for input. If a hotkey associated with a menu entry is pressed, it will boot the associated menu entry immediately. If the timeout expires before either of these happens, it will boot the default entry. In the ‘countdown’ case, it will show a one-line indication of the remaining time.
One could argue if a timeout of 0 can be interrupted by a button press or not but there are a few reason why it should:
- Otherwise I see not how the wanted behavior from the startpost could be possible (booting to the default operating system at default without waiting and only displaying the selection if a related key is pressed).
- The reporter from the upstream report claims that this has worked in the past.
- I think the documentation for GRUB_HIDDEN_TIMEOUT also implies that a timeout of 0 should be interruptable.
On testing this again on Ubuntu 18.10 dev with grub-pc 2.02-2ubuntu13 and this time by not setting GRUB_HIDDEN_TIMEOUT at all, setting GRUB_TIMEOUT to 0.0 and then testing with GRUB_TIMEOUT_STYLE being set to menu (while keeping shift pressed at booting), hidden (while keeping ESC pressed at booting) and coutdown (while keeping ESC pressed at booting) I'm still seing the behavior from the startpost.
But according to the documentation at https:/ /www.gnu. org/software/ grub/manual/ grub/html_ node/Simple- configuration. html it should work:
> ‘GRUB_TIMEOUT_ STYLE’
>
> If this option is unset or set to ‘menu’, then GRUB will display the menu and then wait for the timeout set by ‘GRUB_TIMEOUT’ to expire before booting the default entry. Pressing a key interrupts the timeout.
>
> If this option is set to ‘countdown’ or ‘hidden’, then, before displaying the menu, GRUB will wait for the timeout set by ‘GRUB_TIMEOUT’ to expire. If ESC is pressed during that time, it will display the menu and wait for input. If a hotkey associated with a menu entry is pressed, it will boot the associated menu entry immediately. If the timeout expires before either of these happens, it will boot the default entry. In the ‘countdown’ case, it will show a one-line indication of the remaining time.
One could argue if a timeout of 0 can be interrupted by a button press or not but there are a few reason why it should:
- Otherwise I see not how the wanted behavior from the startpost could be possible (booting to the default operating system at default without waiting and only displaying the selection if a related key is pressed).
- The reporter from the upstream report claims that this has worked in the past.
- I think the documentation for GRUB_HIDDEN_TIMEOUT also implies that a timeout of 0 should be interruptable.