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69 lines
1.9 KiB
Text
69 lines
1.9 KiB
Text
= Using the GRUB2 boot prompt
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[[using-the-grub-2-boot-prompt]]
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If improperly configured, *GRUB2* may fail to load and subsequently drop
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to a boot prompt. To boot into the system, proceed as follows:
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. Load the XFS and LVM modules
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+
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----
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insmod xfs
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insmod lvm
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----
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. List the drives which *GRUB2* sees:
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+
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----
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grub2> ls
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----
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. Examine the output to understand the partition table of the `/dev/sda` device. The following example shows a DOS partition table with three partitions:
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----
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(hd0) (hd0,msdos3) (hd0,msdos2) (hd0,msdos1)
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----
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A GPT partition table of the `/dev/sda` device with four partitions could look like this:
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----
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(hd0) (hd0,gpt4) (hd0,gpt3) (hd0,gpt2) (hd0,gpt1)
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----
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. Probe each partition of the drive and locate your `vmlinuz` and `initramfs` files.
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----
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ls (hd0,1)/
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----
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The outcome of the previous command will list the files on `/dev/sda1`. The partition that contains the `/boot` directory is the correct one. There you will search for the full names of the `vmlinuz` and `initramfs` files.
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. Set the root partition.
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----
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grub> set root=(hd0,3)
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----
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This command tells the bootloader, that the root partition is the third partition on the first drive. This would correspond to the `/dev/sda3` device.
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. Set the desired kernel.
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----
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grub> linux (hd0,1)/vmlinuz-3.0.0-1.fc16.i686 root=/dev/sda3 rhgb quiet selinux=0
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# NOTE : add other kernel args if you need them
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# NOTE : change the numbers to match your system
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----
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. Set the desired `initrd`.
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----
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grub> initrd (hd0,1)/initramfs-3.0.0-1.fc16.i686.img
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# NOTE : change the numbers to match your system
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----
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. Boot with the selected settings.
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+
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----
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grub> boot
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----
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. To restore the bootloader's functionality, regenerate the *GRUB2* configuration file and reinstall the bootloader into the MBR, as described in xref:adding-other-operating-systems-grub2[Adding other operating systems to the *GRUB2* menu].
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