Ubuntu – How to run update-grub


I went into Live CD and activated Terminal. Then, I typed gksu nautilus to gain temporary access to my root directory. Once the Manager window opened, I clicked on File System and navigated to the /etc/default/grub directory. I then double clicked on the Grub file to make changes to the TIMEOUT and TIMEOUT_QUIET.

I saved the file after I made the changes. Then I went back to the terminal mode and typed:

gksu update-grub

The error message I got was:

Can not find a device for / (is /dev mounted?)

I'm not sure what to do at this point. How can I run update-grub to update the changes? Thanks in advance for your help. Please be very detailed and specific with your response as I am totally new to this environment.

Best Answer

Phase 1 - Note: don't use a Live CD.

  • In your Ubuntu open a terminal (press Ctrl+Alt+T at the same time)
  • Type gedit admin:///etc/default/grub
    This will run text-editor gedit, if you're using another one just type the name of it instead of gedit.
  • Make the changes you would like to make and save them.
  • Close gedit.
    Your terminal should still be open.
  • In the terminal type sudo update-grub, wait for the update to finish.
  • Reboot your computer.

Phase 2 - After you have logged into your system

  • Open a terminal again (Ctrl+Alt+T).
  • Type in the terminal gksu gedit /etc/default/grub
  • To see the grub-menu at boot time,
    comment or remove the following line: GRUB_HIDDEN_TIMEOUT=0
    • To comment, add # at the beginning of this line, the result will be #GRUB_HIDDEN_TIMEOUT=0
  • Save the file.
  • Again in the terminal run sudo update-grub.

If seeing the grub menu at boot is the only thing you want you should undo earlier changes to the file.