How can you restore the Grub in Ubuntu? Ubuntu Grub Console Typically, the GNU GRUB minimal console appears on your screen, as illustrated on the below screenshot. You try to boot your Ubuntu server machine and you see that the operating systems no longer starts-up and you discover that the boot loader program no longer works?
Download Ubuntu Server Edition DVS ISO Image.However, this tutorial will only cover Ubuntu server GRUB rescue procedure, although the same procedure can be successfully applied on any Ubuntu system or on the majority of Debian-based distributions. This procedure has been successfully tested on an Ubuntu 16.04 server edition with the Grub boot loader damaged. In all modern Linux operating systems GRUB is the default boot loader.
Uns ist nicht bekannt, dass es zu einem permanenten Defekt kommen kann, schließen aber jede Haftung in so einem Fall aus.This tutorial will guide you on how to rescue, repair or reinstall a damaged Ubuntu machine which cannot be booted due to the fact that the Grub2 boot loader has been compromised and cannot load the boot loader which transfers the control further to the Linux kernel. Unter Umständen muss der USB-Stick mit einem speziellen Verfahren neu dann initialisiert werden.
Leider steht sowas nie auf der Packung.ĭas oben beschriebene Verfahren kann dazu führen, dass es bei solchen USB-Sticks zu Fehlern kommt. implizit davon aus, dass der USB-Stick mit einem Windows-Dateisystem beschrieben wird, was man aus unserer Sicht durchaus als "Bug" bezeichnen kann. Sie missbrauchen scheinbar bestimmte Speicherbereiche, um Information zur Verwaltung des Flashspeichers abzulegen. Manche USB-Sticks verhalten sich gegenüber Linux nicht transparent. Die Bezeichnung für die Partition /dev/sda1 ist bei Grub ( hd0,0). Das Vorgehen ist aber exakt wie bei der Festplatte. Jetzt fehlt natürlich noch der Kernel, eine initial Ramdisk und eine Konfiguration für GRUB unter /boot/grub/menu.lst. [ Minimal BASH-like line editing is supported. If successful, you will be greeted by the prompt from GRUB: GNU GRUB version 0.96 (640K lower / 3072K upper memory)
If so far you have done everything correctly, and nothing wrong, you should now be able to boot a PC from this USB stick. Important: Do not forget to unmount: umount /mnt Test
Now you can install GRUB in the MBR on the USB disk: grub-install -root-directory=/mnt /dev/sda Since GRUB names hard disks differently to the Linux kernel, we have to create a file by telling GRUB that /dev/sda is its first hard disk: echo '(hd0) /dev/sda' > /mnt/boot/grub/device.map We create this directory and copy the bootloader parts into it, most easily from our development system’s hard drive – which hopefully also boots with GRUB: mkdir -p cp /boot/grub/*stage* /mnt/boot/grub Grub is stored in the directory /boot/grub. First we mount the new partition after /mnt: mount /dev/sda1 /mnt Now we prepare a directory structure for GRUB and install it on the USB stick. of type ext2: mkfs.ext2 /dev/sda1 Install GRUB On this partition we create a file system, e.g. Important: For the kernel to really interpret the new partition table correctly, it may be necessary to unplug and re-plug the USB stick once. This can be done with fdisk /dev/sda or cfdisk /dev/sda, for example. Now we create a partition table with one partition and activate it (bootable flag). In the following we assume that /dev/sda is the same as the USB key.Īttention: the following command irretrievably deletes all data on this device! Make sure beforehand which device file your USB stick really addresses! cat /dev/zero > /dev/sdaĬat: write error: No space left on device If there are no SCSI, SATA or other USB storage devices connected to the system, the device used for the USB stick is usually /dev/sda. The following procedure illustrates how to install a working bootloader on a USB stick:įirst we overwrite the complete stick with zero bytes. You want to boot a Linux system from a USB stick.