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Questions tagged [grub2]

GRUB 2 is the next generation of the GRand Unified Bootloader (GRUB). Ubuntu has used GRUB 2 as the boot loader since 9.10 (Karmic Koala). Commonly referred to as simply "GRUB".

What questions should have this tag?:

  • Questions on how to edit, repair, or troubleshoot GRUB 2
  • Questions on how GRUB 2 works

Some basic definitions:

Bootloader - This is a program which loads the operating system (OS) or other software, after POST (power-on self-test).

Boot Record - Contains information on which OS(s)/program(s) to "boot", and information about where these are located.

Brief introduction to the subject:

From the Ubuntu Wiki page for GRUB 2:

GRUB 2's major improvements over the original GRUB include:

  • Scripting support including conditional statements and functions
  • Dynamic module loading
  • Rescue mode
  • Custom Menus
  • Themes
  • Graphical boot menu support and improved splash capability
  • Boot live CD ISO images directly from hard drive
  • New configuration file structure
  • Non-x86 platform support (such as PowerPC)
  • Universal support for UUIDs (not just Ubuntu)

Important links for learning more:

13224 questions
769
votes
40 answers

How do I remove old kernel versions to clean up the boot menu?

Every time I install a new Linux kernel, it gets left in the grub_config, making the boot menu longer each time. I know I can manually search through the installed packages and remove them. Does Ubuntu provide any easier way to clean them up or…
ImaginaryRobots
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471
votes
8 answers

How do I change the GRUB boot order?

I have both Windows 7 and Ubuntu installed on a shared machine. Because a lot of the non-developers use Windows, I'd like to change the boot order to make it easier for them. Currently the boot order looks like the following: Ubuntu 11.10…
chrisl-921fb74d
  • 11,136
466
votes
10 answers

How to get to the GRUB menu at boot-time?

My system is not dual-boot, I run a standard Ubuntu desktop system "on the metal" (I think running it in a VM is the same). Pressing c while booting does not cause the GRUB menu to appear (which I believe it does for a dual-boot system). How can I…
Peter.O
  • 25,251
435
votes
14 answers

How can I repair grub? (How to get Ubuntu back after installing Windows?)

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu. How can I get Ubuntu back?
Salahuddin
  • 4,911
294
votes
16 answers

How do I set Windows to boot as the default in the boot loader?

How do I set the bootloader so that in my dualboot with Windows 7/Ubuntu 11.04, Windows start up as standard instead of Ubuntu?
Rasmus Mathiesen
  • 3,290
279
votes
11 answers

How do I set the grub timeout and the grub default boot entry?

In Ubuntu 12.04 (or above), how do I set the GRUB time and the default OS (that I see at boot time) as I'm dual-booting Windows (7/8) and Ubuntu (12.04 or above)?
meteors
  • 3,045
262
votes
13 answers

Uninstall GRUB and use Windows bootloader

I have Windows 8 pre-installed, and then I installed GRUB with Ubuntu. Ubuntu is not my thing, so now I want to remove it along with GRUB. From what I have learned, with UEFI, GRUB does not overwrite the windows bootloader in the EFI partition and…
mrolive
  • 2,775
261
votes
3 answers

How do I add a kernel boot parameter?

I need to add the boot parameter foo=bar to my kernel. How can I do this once for testing, and permanently if testing was a success?
htorque
  • 66,086
173
votes
5 answers

How to get grub2 to remember last choice?

Grub2 - Community Ubuntu Documentation says the following: Saving an OS can be achieved by running sudo grub-set-default if DEFAULT=saved is set in /etc/default/grub. It may also be saved if GRUB_SAVEDEFAULT=true is also set in…
Jay Sullivan
  • 2,079
171
votes
8 answers

Set "older" kernel as default grub entry

I installed a mainline kernel for testing purposes. I would like to set grub to boot from the older kernel by default. I know I can set the GRUB_DEFAULT=0 setting for the first page of grub but how do I set it to boot by default from one kernel in…
To Do
  • 15,833
157
votes
3 answers

How do I re-run boot loader?

Running sudo apt-get -f install said that The link /vmlinuz.old is a damaged link and: you may need to re-run your boot loader[grub] Here's the full output: user@chrubuntu:~$ sudo apt-get -f install Reading package lists... Done Building dependency…
TevinYoungz
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  • 10
  • 6
139
votes
3 answers

How do I set 'nomodeset' after I've already installed Ubuntu?

I know that editing the boot options line and adding 'nomodeset' solves the problem of my laptop during LiveCD mode, what I don't know is how to set it at boot up through Grub2 after I've installed Ubuntu. So, my question is; how do I set nomodeset…
Dante Ashton
  • 5,595
130
votes
2 answers

What is the difference between GRUB_CMDLINE_LINUX and GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub

I'm troubleshooting a fn-key brightness control problem on my laptop, so I'm wading through a lot of config options in /etc/default/grub, as you can imagine. However, it's raised a question for me: What's the difference between the lines marked…
analogyschema
  • 1,411
125
votes
2 answers

What do I select for "GRUB install devices" after an update?

After running Update Manager, a debconf window (titled "Configuring grub-pc"), popped up, requiring me to select the appropriateGRUB install devices for my system. I've made no changes to grub or the filesystem recently, and I don't remember what…
belacqua
  • 23,540
115
votes
6 answers

How can I show or hide boot messages when Ubuntu starts?

Is there a way to easily turn on/off showing the boot messages (loading the services) when Ubuntu starts? Is it something in Grub2? I am running 10.04.
Weboide
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