how to repair grub in linux

How to Repair Grub

• Start by doing a simple ls listing to see what partitions are available. ...
• You can see the files of any partition by using another ls command. ...
• Once you have determined the correct partition, you can set it as root with the following commands. ...

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Full Answer

How to get rid of Linux Grub?

How do I update grub menu?

• In your Ubuntu open a terminal (press Ctrl + Alt + T at the same time)
• 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.

How to bypass Grub rescue on a Linux computer?

• What are the Grub files?
• How to repair Grub
• What to do if Grub is completely broken

How to update your Grub in Linux?

Via Grub Terminal

1. Use the set command with no arguments to view the environment variables: set The example output shows that GRUB is set up to boot from (hd0,msdos3) partition:
2. The ls command lists the available partitions on the disk. ls The output shows the partition list. ...
3. Set the boot partition as the value of the root variable. ...
4. Load the normal boot mode. ...

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How to boot Linux from GRUB command line?

System Summary

• ASUS X44C
• Internal hard disk drive 320 GB with 3 primary partitions.
• External hard disk drive 320 GB with 3 primary partitions, 1 extended partition, and 6 logical partitions.
• External hard disk drive has no GRUB bootloader (selecting bootloader), but has only GRUB prompt.

How do I fix corrupted grub in Linux?

The solutionTo fix the problem execute from grub command line: ... Restore boot partition on hd0,0 (first partition on first disk) as in above example from find command. ... Then setup grub on first disk (hd0) – as in above example boot stage1 is located on hd0. ... After command will succeed reboot the server.

How do I restore a grub file in Linux?

Recover/Restore the GRUB – BIOS Based system:Insert RHEL 7 / CentOS 7 latest DVD on the server or attach ISO image using ILO.In case of a Virtual machine, attach the ISO image to the VM.Boot the server using the DVD/ISO image.Choose troubleshooting option once the system is booted in DVD/ISO. ... Choose the rescue mode.More items...•

How do I restore grub loader?

To remove it:Hit Windows + X and select Disk Management .Find the Ubuntu partition. It will probably be a large partition without a drive letter.Be sure you have the correct partition!Right-click the partition and delete or reformat it with a Windows filesystem.

How do I purge and reinstall grub?

Reverting to GRUB LegacyOpen a terminal: Applications, Accessories, Terminal.Optional: Make backup copies of the main GRUB 2 directories and files. sudo cp /etc/default/grub /etc/default/grub.old. ... Remove GRUB 2. sudo apt-get purge grub-pc. ... Install GRUB 0.97. ... With grub installed, the user must still create the menu. ... Reboot.

How do I run boot repair?

Method 1: Startup Repair toolStart the system to the installation media for the installed version of Windows. ... On the Install Windows screen, select Next > Repair your computer.On the Choose an option screen, select Troubleshoot.On the Advanced options screen, select Startup Repair.More items...•

How do I rebuild grub conf?

Rebuild the grub.cfg file by running the grub2-mkconfig -o command as follows:On BIOS-based machines, issue the following command as root : ~]# grub2-mkconfig -o /boot/grub2/grub.cfg.On UEFI-based machines, issue the following command as root : ~]# grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg.

How do I get rid of grub error?

6 AnswersPut the Windows 7 installation/Upgrade disc in the disc drive, and then start the computer (set to boot from CD in BIOS).Press a key when you are prompted.Select a language, a time, a currency, a keyboard or an input method, and then click Next.Click Repair your computer.More items...

How do I manually install grub bootloader?

ResolutionMount root to /mnt. ... Mount /boot to /mnt/boot. ... Mount system pseudo file systems under /mnt. ... "change root" or chroot to /mnt. ... Under /boot/grub, there is a file called "device. ... Launch the grub interactive shell. ... In the interactive shell, you will see a "grub>" prompt. ... Type quit.More items...•

How do I use grub command line?

Booting From grub> The first line sets the partition that the root filesystem is on. The second line tells GRUB the location of the kernel you want to use. Start typing /boot/vmli , and then use tab-completion to fill in the rest. Type root=/dev/sdX to set the location of the root filesystem.

How do I get grub menu on startup?

You can get GRUB to show the menu even if the default GRUB_HIDDEN_TIMEOUT=0 setting is in effect:If your computer uses BIOS for booting, then hold down the Shift key while GRUB is loading to get the boot menu.If your computer uses UEFI for booting, press Esc several times while GRUB is loading to get the boot menu.

How do I get out of grub mode?

If you press escape in grub menu you end up at the grub command prompt.

How do I fix grub rescue after deleting Linux partition?

Solution:Turn on laptop and boot into Ubuntu OS.Launch the command Terminal(Ctrl+Alt+T) from Ubuntu.Type in the command in the terminal window: sudo update-grub.Hit Enter Key.Type in your sudo password when prompt to execute your command.

How do I reset my grub theme?

How to change your grub themeJust download and install. ... Copy/paste the original grub. ... Start grub-customizer and choose your theme. ... Choose the theme, save and reboot. ... Dimensions of grub will be. ... This is the vimix theme from gnome-look.org. ... This is the Arch silence theme from gnome-look.org.More items...

How do I get out of grub rescue mode in Linux?

4 AnswersCommand: ls. ... If you don't know your Ubuntu boot partition, check them one by one: ls (hd0,msdos2)/ ls (hd0,msdos1)/ ... Assuming (hd0,msdos2) is the right partition: set prefix=(hd0,msdos2)/boot/grub set root=(hd0,msdos2) insmod normal normal.Now you'll be able to boot into Ubuntu.

GRUB Boot Issues

The most common reason for GRUB not booting into the operating system is another OS's bootloader overwriting GRUB boot configuration. The problem occurs during an attempt a dual boot with an existing Linux installation. Another reason is the accidental removal of GRUB configuration files.

GRUB Rescue Commands

Below is the list of the commonly used GRUB Rescue commands. Use the commands in the prompts mentioned in the previous section.

Fixing Boot Failure

This tutorial covers two ways to resolve GRUB boot issues, using the GRUB Rescue prompt, and the Boot Repair tool.

How to repair GRUB?

To repair Grub, you may need to know the name of the boot and root partitions where Linux is installed. If you have many partitions on your disk you may not remember which one it is. You can run fsarchiver probe simple or fsarchiver probe detailed from SystemRescuecd to show the list of filesystems of your computer.

What is the root filesystem for Linux Debian?

There we can see that /dev/sda1 is the boot partition, and /dev/sda2 is the root filesystem for Linux-Debian. This is obvious because the labels are appropriate, but it’s not always that simple. All linux root filesystems are supposed to have their init program in /sbin/init.

Can you clone a partition?

disk cloning: you may want to clone your partitions to another disk or another computer for some reason. If you just clone the partitions of the disks, the sectors where Grub is installed may not be copied (eg: sectors before the first partition, or MBR).

Do I have to reinstall Linux?

Fortunately there are solutions to recover your linux installation by reinstalling Grub, and you don’t have to reinstall Linux entirely. All the administration programs required to re-enable Grub are part of the standard Linux installations, so the main problem is to access Linux the first time.

Can you boot a Linux system from a USB stick?

SystemRescueCd allows you to boot a Linux system installed on the disk even if grub is broken. You have to boot SystemRescueCd either from the cdrom, usb stick or the network . The purpose is to just have access to your system so that you can reinstall Grub from your original Linux installation.

How it looks?

There are basically three error messages or screens when GRUB fails to boot. grub>: This is the screen mode you see when GRUB has found everything except the configurationn file. This file probably will be grub.conf. grub rescue>: This is the mode when GRUB 2 is unable to find the GRUB folder or its contents are missing/corrupted.

Basic commands available

These are the commands that can be used when you enter the GRUB 2 terminl mode by pressing "c".

The Rescue Shell

If you get a rescue shell, this usually means that GRUB failed to load the "normal" module for some reason.

What is a GRUB?

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 ...

How does boot repair work?

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.

Is the Grub still there?

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.

Can you change the boot order of a Grub?

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.

Can I boot Ubuntu from USB?

In this case, you have access to your Ubuntu system so you don’t necessarily need to boot from a USB drive. 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.

Reinstall Ubuntu GRUB Boot Loader

1. After you’ve downloaded and burned the Ubuntu ISO image, or created a bootable USB stick, place the bootable media into your appropriate machine drive, reboot the machine and instruct the BIOS to boot into Ubuntu live image.

Manually Reinstall Ubuntu Grub Boot Loader

14.

How to repair GRUB2?

The Boot Repair window will automatically scan your system after you run the boot-repair command. After it scans your system, click the “Recommended repair” button to repair GRUB2 with a single click.

What is GRUB2 boot repair?

Boot Repair is a graphical tool that can repair GRUB2 with a single click. This is the ideal solution to boot problems for most users. If you have the media you installed Ubuntu from, insert it into your computer, restart, and boot from the removable drive. If you don’t, download a Ubuntu live CD and burn it to a disc or create a bootable USB flash ...

Can you use advanced options in Ubuntu?

You can choose to use the advanced options here, but Ubuntu’s wiki recommends you not use the advanced options unless you know what you’re doing. The recommended repair option can fix most problems automatically, and you could mess up your system even more by selecting the wrong advanced options.

How to install boot repair in Ubuntu?

To start the installation of Boot Repair in the Ubuntu live environment, open up a terminal window. To open up a terminal window in the Ubuntu live environment, press the Win key on the keyboard and search for “terminal.”. Or, press Ctrl + Alt + T on the keyboard.

How to make a live USB for Ubuntu?

Step 1: Go to another working PC that you can use in place of your broken Ubuntu PC. You will need a PC to create a bootable Ubuntu live USB. Once on the spare PC, head over to Ubuntu.com, click on the “Download” button.

What happens after a GRUB bootloader is repaired?

After a successful GRUB bootloader repair, a ‘Boot successfully repaired’ message will appears on your screen. It will provide a URL where you will find all the information regarding the boot repair. You can now reboot and system and boot your system with the repaired GRUB bootloader.

Why is my Grub file damaged?

One of the major reasons for damaging the GRUB files is having multiple bootloader directories for different distributions and operating systems. Using Ubuntu and Windows together in a dual boot system is commonly used very often.

Why use Ubuntu server ISO?

Using a Ubuntu server ISO file to repair a Ubuntu desktop or server is clever because the ISO server file size is smaller than the desktop LTS file. It takes a short time to make a bootable file and quick to boot. Here, we will see how to use the Ubuntu server ISO file to recover and repair the GRUB bootloader file on Ubuntu.

Can you run a live test on Linux?

Final Words. One of Linux’s ISO files’ best features lets you look at it before installing it on your machine. You can run a live test on your system; later, you can choose if you want to install it or not. This feature is not only helpful to test drives; it can help to recover your operating system if you accidentally remove or mess up with ...