GRUB2 is the next generation of the GRand Unified Bootloader (GRUB). Ubuntu has used GRUB2 as the boot loader since 9.10 (Karmic Koala). Commonly referred to as simply "GRUB".

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380
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34answers
445k views

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 ...
207
votes
5answers
857k views

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 ...
181
votes
9answers
282k views

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?
144
votes
16answers
376k views

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?
110
votes
3answers
308k views

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)?
100
votes
4answers
231k views

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

This issue came up recently for me (and I've been prompted to lodge it as a specific question about it): My system is not dual-boot, I run a standard Ubuntu desktop system "on the metal" (I think ...
86
votes
2answers
76k views

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 ...
80
votes
2answers
74k views

Diskfilter writes are not supported > What triggers this error?

This message occurs when leaving the Grub menu and before the Ubuntu splash screen. How do I fix the problem to clear the message? And what doe is it mean? error: Diskfilter writes are not ...
61
votes
6answers
8k views

How to secure my laptop so that hacking by physical access is not possible?

I messed up my system earlier, I was greeted with a black screen, when booting in to Ubuntu. When I started up my laptop, I selected the recovery option from the grub menu, and chose fallback at root ...
56
votes
3answers
95k views

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?
50
votes
1answer
73k views

Dual boot Surface Pro with Ubuntu?

How could I setup a dual boot for Ubuntu and Windows 8 on my Microsoft Surface Pro with 128 GB. Note: My dual boot solution is below.
47
votes
4answers
181k views

How do I boot into single-user mode from GRUB?

After changing a few lines in xorg.conf, I can no longer boot Ubuntu (I assume it breaks when trying to load up X), so I need a way to boot into a single-user mode. However, there seems to be zero ...
41
votes
5answers
89k views

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 Lucid.
41
votes
1answer
77k views

How do I boot into a root shell?

When booting to the graphical desktop fails we sometimes are recommended to boot into a "root shell" or to boot in "recovery mode". How do I do that?
38
votes
3answers
43k views

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 ...
37
votes
2answers
130k views

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

I know that editing the boot options line and adding 'nomodeset' solves my laptops problem during LiveCD mode, what I don't know is how to set it at boot up through Grub2 after I've installed Ubuntu. ...
37
votes
6answers
191k views

Recovering GRUB after installing Windows 7? [duplicate]

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 ...
37
votes
2answers
17k views

How do I apt-get -y dist-upgrade without a grub config prompt?

Per Make apt-get (or aptitude) run with -y but not prompt for replacement of configuration files? I did the following: ec2run ami-3c994355 --region us-east-1 -n 1 -t m1.large -z us-east-1d On the ...
36
votes
1answer
73k views

Set “older” kernel as default grub entry

Possible Duplicate: How do I set Windows to boot as the default in the boot loader? How do I change the grub boot order? I installed a mainline kernel for testing purposes. I would like ...
36
votes
1answer
25k views

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 ...
34
votes
4answers
164k views

Grub rescue - error: unknown filesystem

I have a multiboot system set up. The system has three drives. Multiboot is configured with Windows XP, Windows 7, and Ubuntu - all on the first drive. I had a lot of unpartitioned space left on the ...
33
votes
5answers
155k views

I can't get grub menu to show up during boot

After trying (and failing) to install better ATI drivers in 11.10, I've somehow lost my grub menu at boot time. The screen does change to the familiar purple colour, but instead of a list of boot ...
32
votes
3answers
102k views

How can I change/convert a Ubuntu MBR drive to a GPT, and make Ubuntu boot from EFI?

I recently have upgraded my PC, my new Motherboard (ASUS M5A99X EVO) uses UEFi instead of the regular MBR option. I have a Ubuntu 11.10 installation that I did when I had my previous hardware (MSI MS ...
32
votes
5answers
422k views

Recovering moved .mod files using grubrescue

I did a dumb thing... I forgot that Ubuntu 10.04 (Lucid Lynx) switched to GRUB 2 which puts a ton of *.mod files (kernel modules) in /boot/grub. I thought they were soundtrack files put there ...
31
votes
5answers
75k views

How do I run update-grub from a LiveCD?

Okay, so I did something stupid. I was trying to clean up my Grub entries, and accidentally removed all of my Linux kernels from Grub (they're still on the hard drive). So now, obviously, Grub ...
30
votes
5answers
82k views

Windows 10 upgrade lead into grub rescue

I was dual-booting Windows 7 and Linux Ubuntu on my desktop, and today is the day they gave out free Windows 10 upgrades. How exciting! I got the update, and it was installing, and I left to go take ...
29
votes
6answers
379k views

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

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 ...
29
votes
2answers
20k views

How to disable Grub's menu from showing up after failed boot

I am performing a test in which I hard-reboot a machine with Ubuntu during its boot sequence (just before login prompt appears). After the reboot, GRUB's menu shows up with no timeout (not its ...
29
votes
5answers
9k views

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?
27
votes
4answers
87k views

How do I safely change grub2 screen resolution?

I did a fresh install of Ubuntu 11.04 on a HP 550 Notebook. But grub2 isn't really fit in the best screen resolution that this Notebook can support (1280x800). How can I do this without using a ...
27
votes
2answers
22k views

How can I force Ubuntu to boot on a stuck boot menu?

I have Ubuntu Server 11.04, but it is headless (no monitor). The only way I want to be able to access it is remotely via SSH. But, sometimes, say after a power loss, when the server restarts, it will ...
27
votes
4answers
122k views

Failed to get canonical path of /cow

I am trying to install Ubuntu 12.10 for quite some time, and passing hurdles one by one. Now I am in a situation as follows. I have got a PC and 10 GB HDD which will be totally dedicated to Ubuntu so ...
26
votes
2answers
53k views

Ubuntu 14.04 not booting after error message. /tmp could not be mounted

I recently installed Ubuntu 14.04 using WUBI and after installation when it booted it showed an error: Serious errors were found while checking the disk drive for /. There were three options: ...
26
votes
12answers
71k views

Windows 10 upgrade kills grub and boot-repair doesn't help

I've just upgraded to Windows 10 from Windows 8.1 on my partitioned laptop that has Ubuntu 14.04 installed. Grub no longer appeared on boot so I ran boot-repair from an Ubuntu liveUSB. This didn't ...
26
votes
6answers
104k views

How can I boot with an older kernel version?

The latest kernel is causing problems with my sound, which worked fine with an older version. As I have only Ubuntu installed, Grub is not getting displayed while booting. How can I manually choose my ...
25
votes
1answer
34k views

What is vt.handoff=7 parameter in grub.cfg?

I wonder what vt.handoff=7 parameter does. I can not find any good man entries for that... BTW, if you have a nice description about: search --no-floppy --fs-uuid --set=root I would be very happy ...
25
votes
0answers
4k views

How to remove the unwanted entries from the boot menu? [duplicate]

Possible Duplicate: Is there a way to remove/hide old kernel versions? When my system boots up, a big list of some 6 options are shown other than the Windows OS option. They are like : ...
24
votes
1answer
29k views

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

I'm making some changes on my grub file under /etc/defaults/grub in some tutorials I have sudo update-grub and others sudo update-grub2 what is the difference?
23
votes
2answers
41k views

GRUB2: Use maximum detected resolution?

How do I tell GRUB2 to set its resolution (and also the one passed to the kernel) to the maximum one it can detect at time of boot?
22
votes
5answers
6k views

How do I investigate boot and partition issues?

My machine won't boot, or won't choose the right operating system when I choose it in the grub menu, what information do I need to provide in my questions so people can help me?
22
votes
9answers
53k views

Hide GRUB2 menu UNLESS you hold down Shift key: how to make this happen?

I have a Ubuntu - Windows 7 dual-boot set-up, and I would like to have it that my laptop would boot up Windows 7 unless I press down the Shift key right after boot and bring up the Grub2 menu from ...
22
votes
2answers
27k views

How do I customize the GRUB 2 menu?

This is what my GRUB 2 menu looks like so far: I want to do a few things here: I want to rename "Windows Boot Manager (on /dev/sda1)" to just "Windows 8.1". I'd like to rename "Ubuntu" to ...
21
votes
12answers
86k views

How do I hide the GRUB menu showing up in the beginning of boot?

I stopped Dualbooting and I dont want to have to choose the OS anymore and just have it load Ubuntu like normal like before? Any help is appreciated.
21
votes
7answers
87k views

Grub does not show a Windows 8 option after dual boot

So, I've successfully dual-booted my Windows 8 machine with Ubuntu 12.04 . However, I still don't have a convenient method of choosing what OS to load at boot time. After installing Ubuntu, my ...
21
votes
3answers
17k views

How do I find the boot parameters used by the running kernel?

Is there a way to find out with what parameters did the kernel boot? For example if I specify noexec=off at the grub command line? Can I see this sort of info after the system has finished booting?
21
votes
1answer
104k views

Cannot update grub with paramters on live USB

I have booted from a live USB ("Try Ubuntu"), that also has a persistent option set (I used LiLi to create one) to do some tests for this pcie hotplug issue I'm having. I'm trying to test some boot ...
21
votes
6answers
169k views

How to install Windows 7 after Ubuntu and dual boot? [duplicate]

I just installed Ubuntu, a full install removing the prior OS. I was forced to remove Windows 7 from my HP dv6 because of the max four partitions already being there. I didn't lose anything, all ...
21
votes
6answers
3k views
+500

Ubuntu Server 16.04 installs on /sdc but fails to boot

I am doing a clean install of Ubuntu Server 16.04 LTS on a machine with a single internal SSD. After completing the install, the system fails to boot and prints a single line fsck output, with the ...
20
votes
4answers
91k views

How do I reset a lost password (using recovery mode requires me to type the password)?

I need to reset my password. I have followed these steps: How do I reset a lost Administrative (root) password? However, then I go to "root" or "netroot" recovery options, it tells me: Give root ...
20
votes
6answers
55k views

How to boot from non-Ubuntu live ISO images like Fedora or CentOS?

I found that it can be done with loopback as follows menuentry "Lucid ISO" { loopback loop (hd0,1)/boot/iso/ubuntu-10.04-desktop-i386.iso linux (loop)/casper/vmlinuz boot=casper ...