Show or hide grub menu in ubuntu

Ubuntu displays or hides the grub selection menu ubuntu 12.04. After windows is installed, the grub selection menu will be displayed at startup. You can select different versions of ubuntu kernel to start ubuntu, after startup, the corresponding menu is not displayed for selection. You can use the following methods to display the grub menu by referring to the information searched on the network. (I believe that after reading it, I also know how to hide the "?" menu ???): 1. hold down the shift key for the previous Ubuntu version during startup, and there is a prompt for grub loading, press ESC to get the menu when starting grub, so Press ESC to see that the grub interface does not have Ubuntu now. Now, press and hold down 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, you can get a root terminal and then reset the root password.) 2. modify the grub file to complete 1. modify sudo gedit/etc/default/grub as follows: GRUB_HIDDEN_TIMEOUT = 0 # GRUB_HIDDEN_TIMEOUT_QUIET = trueGRUB_TIMEOUT = 0 2. sudo update-grub: First Modify/etc/default/grub. cfg file, refer to the following config file to comment out GRUB_HIDDEN_TIMEOUT = 0 # If you change this file, run 'Update-grub 'afterwards to update #/boot/grub. Cfg. # For full documentation of the options in this file, see: # info-f grub-n 'simple configuration' GRUB_DEFAULT = 0 # GRUB_HIDDEN_TIMEOUT = timeout = trueGRUB_TIMEOUT = 10 GRUB_DISTRIBUTOR = 'lsb _ release-I-s 2>/dev/null | echo Debian 'grub _ javasline_linux_default = "quiet splash" grub_javasline_linux = "" # Uncomment to enable BadRAM filtering, modify to suit your needs # This works with Linu X (no patch required) and with any kernel that obtains # the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...) # GRUB_BADRAM = "0x01234567, 0 xfefefefefe, 0x89abcdef, 0 xefefefef" # Uncomment to disable graphical terminal (grub-pc only) # GRUB_TERMINAL = console # The resolution used on graphical terminal # note that you can use only modes which your graphic card supports via VBE # you can see them In real GRUB with the command 'vbeinfo' # GRUB_GFXMODE = 640x480 # Uncomment if you don't want GRUB to pass "root = UUID = xxx" parameter to Linux # GRUB_DISABLE_LINUX_UUID = true # Uncomment to disable generation of recovery mode menu entries # GRUB_DISABLE_RECOVERY = "true" # Uncomment to get a beep at grub start # GRUB_INIT_TUNE = "480 440 1" and then execute "sudo update-grub ". In this way, the following code will be added in grub. cfg ### BEGIN/etc/grub. d/30_os-prober ### if ["x $ {timeout }"! = "X-1"]; then if keystatus -- shift; then set timeout =-1 else set timeout = 0 fi else if sleep -- interruptible 3; then set timeout = 0 fi ### END/etc/grub. d/30_os-prober ### finally, I will briefly introduce several parameters 1. GRUB_HIDDEN_TIMEOUT = 0 this configuration will affect the menu display. If this option is set, the menu is hidden and the boot screen is displayed. The menu will be hidden unless a # sign is added at the beginning of this line. (# GRUB_HIDDEN_TIMEOUT = 0 ). When GRUB 2 is executed for the first time, it will look for other operating systems. If no other operating system is detected, the menu is hidden. If other operating systems are identified, the menu is displayed. If the value is an integer greater than 0, the system will pause Based on the configured number of seconds, but the menu will not be displayed. 0 indicates that the menu is not displayed or there is no delay. You can press and hold the SHIFT key at startup to forcibly display the menu. During startup, the system checks the SHIFT key status. If the button status cannot be identified, there will be a short delay so that you can press ESC to display the menu. 2. GRUB_HIDDEN_TIMEOUT_QUIET = true. No countdown is displayed. The screen will be blank. False indicates the time configured in GRUB_HIDDEN_TIMEOUT. A countdown timer is displayed on the blank screen. 3. GRUB_TIMEOUT = 10 this command will comply with the GRUB_HIDDEN_TIMEOUT configuration, unless GRUB_HIDDEN_TIMEOUT is commented out (#). If GRUB_HIDDEN_TIMEOUT is enabled, GRUB_TIMEOUT is executed only once when the menu is displayed. If this value is set to-1, the menu will be displayed until the user selects it. The GRUB 2 menu is hidden by default, unless it is detected by other operating systems. If no other operating system exists, this line will be commented out unless the user modifies it. To display the menu at each startup, remove the comments of this line and use a value of 1 or greater.