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This article mainly explains "how to update GRUB recovery system boot for Ubuntu through U disk". The content of the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "how to update GRUB recovery system boot for Ubuntu through U disk".

The motherboard needs to be replaced for work, but I don't want to reinstall the computer. What should I do? In fact, there is no need to reinstall the computer, just reply to boot menu.

1. First, use U disk to make a live CD of ubuntu (that is, U disk system as the USBHDD+ mode of installing the system), and then start with U disk, select try ubuntu, and enter the live CD system.

two。 Then you need to determine whether your / boot is partitioned separately. Generally speaking, there is no separate partition. If you don't know, you can see where your boot is through the GPartion program in live CD. As shown in the following figure, my boot does not have a separate partition, in / dev/sdb1

3a. / boot does not have a separate partition.

In this case, first check the contents of the partition through Gpartition to determine the main partition, that is, /, in which partition, for example, I am in / dev/sdb1, and then mount the partition.

First mount the root directory

The code is as follows:

Sudo su

Mount / dev/sdb1 / mnt

Next, "bind" some required directories to live CD's system.

The code is as follows:

Mount-- bind / dev / mnt/dev

Mount-- bind / proc / mnt/proc

Mount-- bind / sys / mnt/sys

Finally, change the root root directory to / mnt

The code is as follows:

Chroot / mnt

So we switch back to our original system and execute update-grub to update the boot

The code is as follows:

Sudo update-grub

If nothing happens, you can restart to enter the system. The whole process is shown below.

3b. / boot separate partition

In this case, you only need to mount the following / boot partitions after early mount / mnt

The code is as follows:

Sudo su

Mount / dev/sdb1 / mnt

Mkdir / mnt/boot

Mount / dev/sdxy / mnt/boot

Note that sdxy refers to the partition in which / boot is located. The other steps are the same as when / boot is not partitioned separately.

Postscript:

Because I use the GTX 670video card, the motherboard is set to boot from the PCI-E slot where the video card is located, so when starting after boot repair, I found only the cursor flashing. This situation is generally a problem with the video card driver, that is, related settings.

First of all, choose to boot from the Intel integrated video card, successfully enter the system, and uninstall the driver, reinstall the driver, and make relevant settings before it can be used normally.

PS: no password is required to set the sudo boot entry

If you want to set a boot entry that requires sudo permission to execute without entering a password, you need to add the program to / etc/sudoers. To line this, first execute sudo visudo and add the following line at the end of the file

The code is as follows:

ALL=NOPASSWD:/usr/local/cuda-6.5/samples/bin/x86_64/linux/release/deviceQuery

Then create a new entry in the statup applications of ubuntu, which is filled in the command field.

The code is as follows:

Sudo / usr/local/cuda-6.5/samples/bin/x86_64/linux/release/deviceQuery

Thank you for your reading, the above is the content of "how to update GRUB recovery system boot for Ubuntu through U disk". After the study of this article, I believe you have a deeper understanding of how to update GRUB recovery system boot for Ubuntu through U disk, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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