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How to Edit & Repair GRUB Boot Menu Using Commands

GRUB or Grand Unified Bootloader is a bootloader package developed to allow users to select from two or more operating systems installed on a single disk. GRUB is what makes dual booting a PC with Windows and a Linux distribution such as Ubuntu possible. You can always install two operating systems on a disk but you’ll only be able to boot one unless the bootloader allows you to choose. If anything goes wrong, you can easily fix, edit and repair the GRUB boot menu using commands.

GRUB is popular among people who use dual boot setups. If you’re using a dual boot setup, you’re most probably making use of GRUB whether you’re aware or not. Sometimes, when you install Windows after installing Linux, or as it is my case, Ubuntu, it breaks GRUB. GRUB is still there but the Windows bootloader takes preference over it, thus booting right into Windows. Today, we’ll see how to edit or repair GRUB boot menu.

Boot Repair

Repairing GRUB can be done in two ways. There’s a graphical way, which is easier and you will know what you’re doing. There’s a command-line way which we will try to avoid here for two reasons. It’s difficult, in the sense that it will require a lot more explanation without which you won’t know exactly what you did to your system. The graphical way is also harmless, meaning you can do it wrong and your data will still be very safe, waiting for you to try again and do it right. The only con is that it requires that you have a bootable Ubuntu disk or USB and a working internet connection. This isn’t a big deal since Ubuntu is available for free and it’s easy to create a bootable Ubuntu drive.

Another scenario would be that you can access Ubuntu and GRUB boots alright, but it does not show Windows or any other OS you may have installed. In this case, you have access to your Ubuntu system so you don’t necessarily need to boot from a USB drive.

  1. Boot your PC via a bootable Ubuntu drive and select Try Ubuntu. This allows you to use a Live Ubuntu session directly from your USB drive without having to install anything.  This step is not required if you can boot into Ubuntu installed on your PC.
  2. Whichever be the case, launch a Terminal window when you’re in Ubuntu. The quickest way to do this would be to press Ctrl+Alt+T. In the Terminal window, use the following commands one by one to install Boot repair.
    sudo add-apt-repository ppa:yannubuntu/boot-repair
    sudo apt-get update
    sudo apt-get install -y boot-repair

Steps to Repair GRUB Boot Menu

  1. Once boot repair is installed, you can quickly search for it by pressing the Windows key and typing boot repair. Launch Boot repair.boot repair ubuntu
  2. It takes a little time to load up and when it does, select Recommended repairGRUB Boot repair tool
  3. Boot repair will guide you through the entire process. You will be required to push commands through the Terminal and make the necessary choices. Boot repair takes care of most of the other things that you would otherwise have to manually do via more complex commands. It also lets you copy the commands so you can simply paste them into the terminal and execute them easily.

Steps to edit GRUB Boot Menu

GRUB doesn’t require repairing very often, but you might not be in love with the default look. You can quite easily change how the GRUB bootloader menu looks to something more pleasing to the eye. You can also change the boot order, so it would boot into your OS of choice by default unless you choose otherwise at the time of boot.  GRUB can be edited using a tool called GRUB Customizer. To install it, just execute the following commands in a Terminal window.

sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer

GRUB customizer list configuration

As you can see above, I’ve select Windows to be the first choice. Usually, the list starts with Windows at the bottom. To move any listing up or down, select it and just click on the arrow buttons on the top.grub customizer appearance settings

In the General settings tab, you can choose if GRUB should boot by default to the first entry in the boot menu or boot to the OS you previously booted into. There are some other settings too as you can see above.

grub customizer general settings

In the Appearance settings tab, you can change the appearance, obviously. It lets you manually select the background image or color, font, and highlight color as well as the font size. You can also install pre-built themes from the internet.

Be very sure of what you do with GRUB customizer though because any incompatible changes can break GRUB, in which case you will have to repair it.

Read next: Show Complete Date & Time in Ubuntu GNOME Top Panel

4 thoughts on “How to Edit & Repair GRUB Boot Menu Using Commands”

  1. I have a dual boot laptop. My primary OS is Neon. A while ago I decided to add Ubuntu Studio. Originally, in the Bios I could choose which boot partition to use. If I set it to Neon, I’d see the Neon boot menu, if I chose Studio, I’d see it’s boot menu, and if Windows then no boot menu at all. Ever since I installed Neon, if I didn’t select Neon quickly at the menu, the computer would freeze and I’d have to reboot again. This didn’t seem to be the issue with the Studio menu, so I’ve left it on that even though I haven’t actually booted into Studio in a long time. I decided to get rid of Studio and just go with Neon. However, even after changing the Bios to load the Neon boot partition, it goes to the grub rescue screen. I’ve used Boot Repair many times over the years and never had any issues with it. But today I can’t get it to work.

    I have a couple live disks (Neon and Studio) that I’ve tried, each have the same results.

    The first issue is that it complains that I have “legacy” Windows and the boot of my PC is in EFI mode and that I should change it to Bios-compatibility/CSM/Legacy mode. First I tried telling it to go on anyway and it gave me the second issue, which I’ll explain in a bit. Then I tried going into the Bios and changing it from UEFI to Legacy, rebooted and tried Boot Repair again. It came back with the same error. When I tell Boot Repair to go on anyway, it then comes back with the second error saying ‘dpkg-error detected. terminal (run) “sudo chroot “/mnt/boot-sav/sda8″ dpkg –configure -a”. So I do that and then get this error “dpkg: error: unable to access the dpkg database directory /var/lib/dpkg: No such file or directory”. /var/lib/dpkg does exist.

    I can’t get any further than this. Any ideas would be greatly appreciated. I really don’t want to reinstall Neon to get past this.

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