Ubuntu-how to enter the grub interface and single mode when only one Ubuntu system is installed to modify the root password

When Ubuntu only installs one system, the grub interface is not displayed by default.

In earlier Ubuntu versions, when grub is started, there is a prompt for grub loading, Press ESC to get the menu, so Press ESC to see the grub Interface

Now Ubuntu is gone, and the current practice is to press the Shift key during startup to see the grub interface.

Next, modify the startup parameter, add single, and press Ctrl + X to start the ncurse interface. Select drop to root prompt to get a root terminal.

Then you can reset the root password.