From f6cfd66f0d1c73efb31e7ed477026e723db49739 Mon Sep 17 00:00:00 2001 From: DarkSun Date: Sun, 22 Dec 2019 00:53:43 +0800 Subject: [PATCH] =?UTF-8?q?=E9=80=89=E9=A2=98:=2020191222=20How=20to=20Upd?= =?UTF-8?q?ate=20Grub=20on=20Ubuntu=20and=20Other=20Linux=20Distributions?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit sources/tech/20191222 How to Update Grub on Ubuntu and Other Linux Distributions.md --- ...on Ubuntu and Other Linux Distributions.md | 127 ++++++++++++++++++ 1 file changed, 127 insertions(+) create mode 100644 sources/tech/20191222 How to Update Grub on Ubuntu and Other Linux Distributions.md diff --git a/sources/tech/20191222 How to Update Grub on Ubuntu and Other Linux Distributions.md b/sources/tech/20191222 How to Update Grub on Ubuntu and Other Linux Distributions.md new file mode 100644 index 0000000000..a969c37867 --- /dev/null +++ b/sources/tech/20191222 How to Update Grub on Ubuntu and Other Linux Distributions.md @@ -0,0 +1,127 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How to Update Grub on Ubuntu and Other Linux Distributions) +[#]: via: (https://itsfoss.com/update-grub/) +[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/) + +How to Update Grub on Ubuntu and Other Linux Distributions +====== + +In this tutorial, you’ll learn to update grub on Ubuntu or any other Linux distribution. You’ll also learn a thing or two about how this grub update process works. + +### How to update grub + +Ubuntu and many other Linux distributions provide a handy command line utility called update-grub. + +To update grub, all you have to do is to run this command in the terminal with sudo. + +``` +sudo update-grub +``` + +You should see an output like this: + +``` +[email protected]:~$ sudo update-grub +[sudo] password for abhishek: +Sourcing file `/etc/default/grub' +Generating grub configuration file ... +Found linux image: /boot/vmlinuz-5.0.0-37-generic +Found initrd image: /boot/initrd.img-5.0.0-37-generic +Found linux image: /boot/vmlinuz-5.0.0-36-generic +Found initrd image: /boot/initrd.img-5.0.0-36-generic +Found linux image: /boot/vmlinuz-5.0.0-31-generic +Found initrd image: /boot/initrd.img-5.0.0-31-generic +Found Ubuntu 19.10 (19.10) on /dev/sda4 +Found MX 19 patito feo (19) on /dev/sdb1 +Adding boot menu entry for EFI firmware configuration +done +``` + +You may see a similar command called update-grub2. No need to be alarmed or confused between update-grub and update-grub2. Both of these commands do the same action. + +Around ten years ago, when grub2 was just introduced, update-grub2 command was also introduced. Today, update-grub2 is just a symbolic link to update-grub and both update grub2 configuration (because grub2 is the default). + +#### Can’t find update-grub command? Here’s what to do in that case + +It’s possible that your Linux distribution might not have update-grub command available. + +What do you do in that case? How do you update grub on such a Linux distribution? + +There is no need to panic. The update-grub command is simply a stub for running ‘grub-mkconfig -o /boot/grub/grub.cfg’ to generate grub2 config file. + +Which means that you can update grub with the following command on any Linux distribution: + +``` +sudo grub-mkconfig -o /boot/grub/grub.cfg +``` + +Of course, remembering update-grub command is a lot easier than the above command and this is the reason why it was created in the first place. + +### How does update-grub work? + +When you install a Linux distribution, it (usually) asks you to install the [grub boot loader][1]. + +Part of grub is installed on the MBR/ESP partition. Rest of the grub lies in /boo/grub directory of the Linux distributions. + +As per its [man page][2], update-grub works by looking into the /boot directory. All the files starting with [vmlinuz-][3] will be treated as kernels and they will get a grub menu entry. It will also add initrd lines for [ramdisk][4] images found with the same version as kernels found. + +It also looks into all disk partitions for other operating systems with [os-prober][5]. If it finds other operating systems, it adds them to the grub menu. + +![Representational image of Grub Menu][6] + +### Why would you need to update grub? + +There could be a number of scenarios when you need to update grub. + +Suppose you changed the grub config file (/etc/default/grub) to [change the default boot order][7] or reduce the default boot time. Your changes won’t take into effect unless you update the grub. + +Another scenario is when you have multiple Linux distributions installed on the same system. + +For example, on my Intel NUC, I have two disks. The first disk had Ubuntu 19.10 and then I installed Ubuntu 18.04 on it. The second OS (Ubuntu 18.04) also installed its own grub and now the grub screen is controlled by Ubuntu 18.04 grub. + +On the second disk, I installed MX Linux but I didn’t install grub this time. I want the existing grub (controlled by Ubuntu 18.04) to handle all the OS entries. + +Now, in this scenario, the grub on Ubuntu 18.04 needs to be updated so that it can see [MX Linux][8]. + +![][9] + +As you can see in the image above, when I update the grub, it finds various Linux kernels installed on 18.04 along with Ubuntu 19.10 and MX Linux on different partition. + +If I want MX Linux to control the grub, I can install grub on MX Linux with [grub-install][10] command and then the grub on MX Linux will start controlling the grub screen. You get the gist, right? + +Using a GUI tool like [Grub Customizer][11] is a simpler way to make changes in grub. + +**In the end…** + +Initially, I had intended to keep it a short article as a quick tip. But then I thought of explaining a few things associated with it so that (relatively) new Linux users could learn more than just a simple command. + +Did you like it? Do you have some questions or suggestions? Please feel free to leave a comment. + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/update-grub/ + +作者：[Abhishek Prakash][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://itsfoss.com/author/abhishek/ +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/GNU_GRUB +[2]: https://manpages.debian.org/testing/grub-legacy/update-grub.8.en.html +[3]: https://www.ibm.com/developerworks/community/blogs/mhhaque/entry/anatomy_of_the_initrd_and_vmlinuz?lang=en +[4]: https://en.wikipedia.org/wiki/Initial_ramdisk +[5]: https://packages.debian.org/sid/utils/os-prober +[6]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/12/grub_screen.png?ssl=1 +[7]: https://itsfoss.com/grub-customizer-ubuntu/ +[8]: https://mxlinux.org/ +[9]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/12/update_grub.png?ssl=1 +[10]: https://www.gnu.org/software/grub/manual/grub/html_node/Installing-GRUB-using-grub_002dinstall.html +[11]: https://itsfoss.com/customize-grub-linux/