I tried to update my grub config file to timeout to 0 value, so OS starts quickly. I modified /etc/default/grub configuration file on my Ubuntu 18.04 and then ran:

sudo update-grub

and it didn't work. I also ran:

sudo grub-mkconfig
sudo update-grub

but they didn't work.

I searched a lot on the web to solve this issue, but all guides say to run the update-grub command to update grub by /etc/default/grub config file. I don't know if is Ubuntu 18.04 that handles grub files in a different way, but I cannot update my grub with my parameters.

This is my /etc/default/grub file:

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
# info -f grub -n 'Simple configuration'

GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)

# Uncomment to disable graphical terminal (grub-pc only)

# 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'

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux

# Uncomment to disable generation of recovery mode menu entries

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"
  • 3
    Please edit your question and include your modified grub config file. Otherwise we're just trying to guess what you did. – Organic Marble May 14 '18 at 12:04
  • Do you have other distributions installed (dual boot)? – mook765 May 14 '18 at 12:22
  • it didn't work mean that my grub timeout is still set to 10 sec as by default @Melebius – Bob91 May 14 '18 at 12:27
  • I have windows in the same ssd and other distros installed on other hdd, but last month i had fedora 27 (instead of ubuntu 18) and it worked when i changed grub config file, so i think the other distros aren't the causes of this behavior @mook765 – Bob91 May 14 '18 at 12:35
  • 1
    Could you please run Boot-Info and edit your question to include a link to its resulting info log? Thanks. – David Foerster May 15 '18 at 13:48

In /boot/grub/grub.cfg file there is a condition, almost at the end of the file, that sets the timeout to 10 if the timeout is set to 0. In other words, if you set the timeout to 0 in your /etc/default/grub and then update grub, the condition above reset it to 10 seconds.

if [ "${timeout}" = 0 ]; then
     set timeout=10

However, /boot/grub/grub.cfg is a read-only file and I cannot remove that condition. I made some tests with different values of the timeout in /etc/default/grub. I tried with 1ms (0.001), 0.1s and 1s and I found out that values below 1 (like 0.1 and 0.001) work in the same way and almost like timeout set to 0.


In my case, the problem was that my system didn't support "recordfail" which caused a separate block to get added to the grub.cfg which defaults to a timeout of 30 seconds. The relevant code in /etc/grub.d/00_header:

if [ "$recordfail_broken" = 1 ]; then
  cat << EOF
if lsefi; then
  set timeout=${GRUB_RECORDFAIL_TIMEOUT:-30}
  if [ x\$feature_timeout_style = xy ] ; then
    set timeout_style=menu

The fix is simply to add a value for GRUB_RECORDFAIL_TIMEOUT in /etc/default/grub and run update-grub again. For example:


# Adjusted timeout for system which doesn't support recordfail

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)

Like the other answers say, uncomment GRUB_HIDDEN_TIMEOUT and run update-grub. Then comment out the

if [ "${timeout}" = 0 ]; then
  set timeout=10

section in /boot/grub/grub.cfg. In vim you can just override the read-only property with an exclamation point :x!. Or you can run

sudo chmod +w /boot/grub/grub.cfg
sudo vim /boot/grub/grub.cfg
sudo chmod -w /boot/grub/grub.cfg

to temporarily have write permission while editing the file.

  • 3
    You are right, but i think everytime you update grub (manually or when there are any os upgrade) the /boot/grub/grub.cfg will recreated with the condition above. – Bob91 May 24 '18 at 16:37
  • 2
    That is true, the file is overwritten on update, as I experienced recently. – asantas93 May 25 '18 at 17:20

Uncomment GRUB_HIDDEN_TIMEOUT=0 and run update-grub again.

  • it doesn't work – Bob91 May 15 '18 at 14:14
  • GRUB_HIDDEN_TIMEOUT=-1 – kuhajeyan Nov 20 '18 at 16:33
  • GRUB_HIDDEN_TIMEOUT=-1 worked on Ubuntu 18.10. – Manish Raj Feb 2 at 10:01

You can set GRUB_TIMEOUT to 0.

The part overwriting timeout value is written in ajust_timeout function in the top of /etc/grub.d/30_os-prober.

ajust_timeout () {
if [ "\${timeout}" = 0]; then
  set timeout=10

So, you can set the value by editing the file and comment out if-block.


You can set GRUB_TIMEOUT to -1.


  • '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. from command info -f grub -n 'Simple configuration – Vijay Feb 20 at 14:10

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