Since the computer has more than one system, the default grub boot menu is hidden and needs to be modified slightly below to display
Do not directly modify the boot/grub/grub.cfg to directly modify the/etc/default/grub, and then Update-grub.
The following three main considerations are:
Grub_hidden_timeout=0
Grub_hidden_timeout_quiet=true
Grub_timeout=0
Explanation of three configuration parameters
/etc/default/grub:
1.grub_hidden_timeout=0
This configuration will affect the menu display. If this option is set, the menu is hidden during this time and the boot screen is displayed.
The menu will be hidden unless you add a # symbol at the beginning of the line. (# grub_hidden_timeout=0).
GRUB 2 will look for other operating systems when it executes for the first time. If no other operating system is detected, the menu will be configured to be hidden. If other operating systems are identified, the menu will be displayed.
If the integer is greater than 0, the system will pause for the number of seconds configured, but the menu will not be displayed.
0 The menu is not displayed and there is no delay.
The user can press and hold the SHIFT key at startup to force the menu to be displayed.
During startup, the system checks the SHIFT key state. If the key state is not recognized, a short delay will allow the user to display the menu by pressing the ESC key.
2.grub_hidden_timeout_quiet=true
True does not display a countdown. The screen will be blank.
False when configured in Grub_hidden_timeout, there will be a countdown timer on the blank screen.
3.grub_timeout=10
This command will conform to the Grub_hidden_timeout configuration unless Grub_hidden_timeout is commented out (#). If Grub_hidden_timeout is enabled, the grub_timeout will be executed only once when the menu is displayed.
Configuring this value to 1 causes the menu to remain displayed until the user chooses.
The GRUB 2 menu is hidden by default, unless other operating systems are detected by the system. If there is no other operating system, the line will be commented out unless the user modifies it. To display the menu at each boot, remove the comment for this line and use a value of 1 or greater.
Ubuntu Startup items, menu changes to prevent hidden
