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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:

12975 questions
289
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
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162
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
  • 15,502
76
votes
6 answers

How to fix "error: unknown filesystem. grub rescue>

I get this error: Error: unknown filesystem. grub rescue> I'm not exactly sure what I did. I believe I installed Ubuntu over Windows on my Acer netbook. I then tried to install Linux Mint, but it wouldn't start installing. I turned the netbook off…
Hjke123
  • 785
72
votes
6 answers

Recovering GRUB after installing Windows 7?

Possible Duplicate: How can I repair GRUB? (How to get Ubuntu back after installing Windows?) I installed Windows 7 after it crashed, and now I am unable to boot Ubuntu. Ubuntu partitions are still there. I tried using Boot-Repair, but it didn't…
Nilav
  • 729
69
votes
1 answer

What is the difference between update-grub and update-grub2?

I'm making some changes on my grub file under /etc/default/grub. In some tutorials I have seen sudo update-grub and others sudo update-grub2. What is the difference?
user23907
66
votes
8 answers

How can I edit my Grub bootloader entries (Hide, Rename, Remove)?

So basically I have a pretty flooded Grub bootloader, with older linux versions, 3 operating systems and memtests. What I want is to leave the operating systems only. I need to know how to do it manually, and I need someone to tell me what should I…
Shahe Tajiryan
  • 2,770
46
votes
6 answers

Decrease GRUB timeout

The GRUB timeout is 8 seconds. Can this be turned down to 2 or 3 seconds? What is the best way to do this?
700 Software
  • 2,267
45
votes
3 answers

Grub update warning in Ubuntu 14.04

I tried to update Grub so I run: sudo update-grub Generating grub configuration file ... Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported. What exactly this warning wants to be changed? (I…
JoKeR
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45
votes
9 answers

What to do when I get an "attempt to read or write outside of disk 'hd0'" error and Boot Repair does not solve the problem?

I tried to install Xubuntu 13.10 on an older computer. I noticed some difficulties during installation that may be relevant to my problems. Notably: The screen resolution was extremely low. The windows were much larger than the screen and I had to…
Martin Drozdik
  • 3,185
44
votes
1 answer

How do I boot into recovery mode?

I recently tried booting into the Grub2's menu entry "Ubuntu GNU/Linux, with Linux 3.2.0-24-generic-pae (Recovery Mode) just to see what was there. It booted successfully, but I had no idea what to do after I was there. My question is where can I…
user18432
  • 1,147
41
votes
2 answers

Is it possible to verify grub installation without rebooting?

I've been bitten by this so many times, and today after the openssl updates in my server grub complained that I should install it again since the "hard disks that it was previously installed do not exist". I have a raid 1 installation with the…
mobius
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26
votes
4 answers

`install-grub` claims that I have multiple partiton labels and that embedding is impossible

I am trying to get GRUB installed on my non-booting desktop computer, but I am encountering several errors. Other sources discussing these errors have ascribed them to either a lack of free disk space before the first partition (I have the requisite…
AJMansfield
  • 595
21
votes
7 answers

Cannot get grub menu to timeout (or go away)

I am running Ubuntu 12.04. I cannot for the life of me get the grub menu (with options) to go away. I would like it to auto-boot into the first option. I've edited /etc/default/grub so that it looks like the…
Eric
  • 311
20
votes
2 answers

How do I edit the boot order in the GRUB menu to have Windows first?

I have a dual boot on my computer of Windows 7 and Xubuntu 12.10. The Linux boot is 1st and the Windows 2nd. I would like to reverse the boot order in the GRUB menu. I need to know the steps to go about editing GRUB. I do most of my work on Windows…
user138310
  • 201
17
votes
3 answers

How to select GRUB install device

I apologize in advance for asking a question I suspect is very, very simple. I just got a dedicated server running Ubuntu and I'm using SSH to access it. I ran sudo apt-get dist-upgrade and got the following error message: "The Grub boot loader was…
David Vogel
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