grub4dos uses the BIOS to access hardware (although it does have it's own USB 2. This means that the next command, chainloader , is executed without the target partition specified (as the target partition is the same, now). cfg", or download the attached file. It’s called GRUB Rescue. List the folders and files on the root device: ls -l / ls -l /AIO ls -l /EFI. GRUB allows a number of useful commands in its command line interface. This is done from the command line. To rewrite the partition table when you reboot, you can stuck with this grub rescue prompt. The command-line in GRUB2 (a popular bootloader) offers admins a great tool for managing and fixing GRUB as well as other parts of the computer system. Since then GRUB 2 (actually at time of update 1. lets see how to do it. For this reason, many people prefer to dual-boot Linux with Windows. conf file and the splash screen image file resides in the /boot partition. The command we are using is still part of your Linux installation. This guide will show you how to find out the amount of disk space a file or folder is taking up using the Linux command line. conf file has the appropriate commands to start the installed systems, GRUB will wait for an amount of time specified in grub. Now use update-grub command to re-generate a GRUB2 config file in /boot based on these changes. When I boot into Ubuntu it makes memtest the default boot menu option. bash, and accepts only certain GRUB-specific commands, documented by various Linux distributions. Report bugs to. To enter the GRUB shell from a running system, just type grub on the command prompt. We can access this from a running system or from within the GRUB menu. Just don't forget to type 'sudo update-grub' in a terminal window after editing the grub file. This command always fails until you enter a valid password, so you can use it, like this: title Boot DOS lock rootnoverify (hd0,1) makeactive chainload +1 You should insert lock right after title, because any user can execute commands in an entry, until GRUB encounters lock. Although you can scan and boot into most of the operating systems installed on computers such as Windows, Linux, FreeBSD and macOS from the AIO Boot’s Grub2 menu. [10] Once boot options have been selected, GRUB loads the selected kernel into memory and passes control to the kernel. Pour être acceptées, ces options doivent être séparées de la commande et des autres options présentes par un espace. This command uses the more flexible command "install" in the backend and installs GRUB into the device INSTALL_DEVICE. The boot command is implied and thus automatically executed at the end of each menu entry, so it does not need to be written into the menu file. – Do not edit this file directly. Whilst this is annoying I could live with it if I were able to change the default back from the grub command line available from the boot menu. Hopefully, the tips and tricks in this article will fix a Linux PC that won’t boot in most cases. It also works on Windows 7. While installing the new Grub, it will ask you to add extra kernel options. set default OS. Some of these parameters are understood by the Linux kernel, some are understood by Fatdog64 system scripts. How change GRUB command line to graphical interface? Hi, I am i new Unix linux user. The boot command is implied and thus automatically executed at the end of each menu entry, so it does not need to be written into the menu file. GRUB vs LILO The two boot loaders that Red Hat Linux provides for x86 architecture are the Grand Unified Boot Loader (GRUB) and the Linux Loader (LILO). To update Grub on operating systems that do not have an "update-grub" function, run this command in the terminal: sudo grub-mkconfig -o / boot / grub / grub. Start by issuing the root directive as described above. GRUB bootloader has powerful command line interface that can be used to solve boot problems. After few seconds, once it found Windows (10) bootloader, you will get the prompt again. GRUB is what makes dual booting a PC with Windows and a Linux distribution such as Ubuntu possible. 4-5, 6, 7, and 8 all boot to a grub command line. Our software and services protect against more risks at more points, more completely and efficiently, enabling confidence wherever information is used or stored. Booting GNU/Linux Manually with GRUB Prompt This is a recovery tutorial about using GRUB prompt to boot an operating system inside a hard disk drive. GNU GRUB (short for GNU GRand Unified Bootloader) is a boot loader package from the GNU Project. cfg) by meanhacker XDA Developers was founded by developers, for developers. In summary, I had to tell GRUB to boot from the most recent kernel and this is the way to do it: set root=(hdX,Y) linux /vmlinuz root=/dev/sdXY ro initrd /initrd. The "/boot/grub2/grub. This tutorial is about the grub2 boot loader - i. It is important to use the latest GRUB package available to install GRUB. My resolution is 1920×1080. Some of the commands accept options after their name; these options should be separated from the command and other options on that line by space characters. If that works, you can make it permanent by editing your /etc/default/grub file, and changing the line to look like this: GRUB_CMDLINE_LINUX="nomodeset" Then run: sudo update-grub This isn't the best solution, since it seems to put your machine into software rendering. Save the changes and exit the editor & update grub using either of the commands; # update-grub. GRUB has both a simple menu interface for choosing preset entries from a configuration file, and a highly flexible command-line for performing any desired combination of boot commands. I also downloaded GParted livecd 0. GRUB repair when the grub folder is missing or corrupted If the contents of /boot/grub/ directory is accidentally deleted or corrupted somehow, the rescue process is little different. By the end of the restore GRUB, restart the computer. Using GRUB 2. Previously, you would edit /boot/grub/grub. Grub now features an advanced rescue mode, truly a godsend for people who somehow messed their MBR tables up. the grub> prompt that you see when you boot from a device which has grub2 installed. Then I ran the command grub2-mkconfig > /boot/grub2/grub. Most Grub installations on Linux are located at /boot/grub/, so the following command should work correctly to update Grub. Diese Optionen sind vom Befehl und anderen Optionen auf derselben Zeile durch Leerzeichen zu trennen. Important: If you have a separate boot partition, skip the above command and mount the boot partition at /mnt/ubuntu/boot instead. cfg which instructs GRUB to use ${cmdpath}/grub. If the info and grub programs are properly installed at your site, the command. ls (hd0,1)/ The linux root partition will contain /bin, /boot, /lib etc. lst file is not found, grub4dos will display a grub> command prompt. cfg, but you should not edit that as it will be overwritten on subsequent calls to update-grub. Changed Bug title to `grub2 is missing hide/unhide commands' from `grub-common: Update to grub2 fails with Windows XP partitions'. Grub Command Line Manual Boot Alternatively, enter the GRUB command line and run the command vbeinfo. after this I get the windows loader and then the grub menu. Or the GRUB package from the installation CD-ROM is used. See the Archlinux GRUB documentation. grub" is the default parser. Find Out All Information About The Command. GRUB can be used via the menu driven interface and command line interface. GRUB v1 for Debian (package grub) can be installed with:. conf file has the appropriate commands to start the installed systems, GRUB will wait for an amount of time specified in grub. If you omit HIGHLIGHT, then the inverted color of NORMAL is used for the highlighted line. You can download Windows 10 from another PC. At the Microsoft Setup menu, press R. Now you can execute the linux command. The GRUB files for the distribution that was installed will be under a folder of the same name as the distribution. You can increase or decrease this timeout setting. We can see that grub has found a Linux file system EXT3, and set root to it. The grub folder must exist and contain the necessary GRUB 2 files and modules. Repair GRUB: error: unknown filesystem. You can use grub's search command to find it. for that we need access to the /boot/grub directory, which contains the grub modules. I can see the background in grub customizer but when I reboot I still see the black screen. command line: The grub2 packages contain commands for installing a bootloader and for creating a bootloader It is generally safe to directly edit /boot/grub2/grub. Issue the grub2-mkconfig command to re-create the grub. Press 'e' to display the GRUB edit menu. When you use the Anaconda installer to install Red Hat, the GRUB boot loader is selected by default. Placing passwords or locking menu items (in the Grub configuration files) does not prevent a user from booting manually using commands entered at the grub command-line. Lesson 2 | Lesson 4. Once you set a password, you cannot edit any grub entries, or pass arguments to the kernel from the grub command line without entering the password. Step 5: Re-install Grub packages. Editing the GRUB Maine menu: 1. If you're familiar enough with the GRUB 2 configuration file format, you can boot your computer by typing commands at the shell. The way arround this is to make grub load SeaBIOS which then loads ipxe. Now close the terminal and restart the laptop. Important: If you have a separate boot partition, skip the above command and mount the boot partition at /mnt/ubuntu/boot instead. Installing GRUB Package. Step 5: Re-install Grub packages. The color NORMAL is used for most lines in the menu, and the color HIGHLIGHT is used to highlight the line where the cursor points. Only the names are similar. cfg file as this command reconfigures grub. Finally, as mentioned previously, the Rescue and Recovery partition should be hidden from Windows. set default OS. Commandes GRUB. Note that the native gdb "p vI2Matrix" (last command) was much less informative. GRUB bootloader has powerful command line interface that can be used to solve boot problems. The GRUB files for the distribution that was installed will be under a folder of the same name as the distribution. Grub now features an advanced rescue mode, truly a godsend for people who somehow messed their MBR tables up. cfg which instructs GRUB to use ${cmdpath}/grub. The grub-mkstandalone command can be used to create a single GRUB binary. They are also known as "boot options". This guide will show you how to find out the amount of disk space a file or folder is taking up using the Linux command line. Modifying the Linux Grub boot loader's options Posted in Linux/Unix/BSD - Last updated Apr. Placing passwords or locking menu items (in the Grub configuration files) does not prevent a user from booting manually using commands entered at the grub command-line. Linux Mint is free of charge (thanks to your donations and adverts on the website) and we hope you'll enjoy it. But after booting either Linux or Windows then rebooting, I GRUB starts in command line mode, as seen in the following screenshot: There is probably a command that I can type to boot from that prompt, but I don't know it. At a minimum add commands/colortest. You can download Windows 10 from another PC. We can see that grub has found a Linux file system EXT3, and set root to it. The above two command will put grub in regular command mode. Anyway, I need help with how I can fix the MBR from the grub rescue screen WITHOUT a CD/USB to repair. The GRUB 2 configuration file is /boot/grub2/grub. In a newer version of GRUB, i. It can also embed an initial grub. As we deleted the previous Grub, we deleted the messed up settings as well as any favourite settings stored in it. The main configuration file for grub2 is /boot/grub2/grub. This means you're using a bare-bones version of the GRUB rescue shell, and you won't be able to use the Tab key to complete your commands. cfg file, along with the menu settings read from the /etc/default/grub file. Formatting hd from grub If this is your first visit, be sure to check out the FAQ by clicking the link above. GRUB understand filesystems and can search them for files, helping you find file names and boot unfamiliar systems. grub4dos uses the BIOS to access hardware (although it does have it's own USB 2. I think this is because you deleted some partitions that work containing some booting files, and those are required when you start a computer. should give you access to the complete manual. 1 Pager support, 6. GRUB bootloader has powerful command line interface that can be used to solve boot problems. Just bring back the grub prompt You could probably fix it by running the following command in the SteamOS terminal: sudo update-grub. This is the extra step you need in case of GRUB2. Restart the system. 10 Ji m I'm a freelance blogger who started using Ubuntu 5+ years ago and wishes to share my experiences and some useful tips with Ubuntu beginners and lovers. I tried re-installing, re-formating, various GRUB commands and nothing worked. 0 driver if you install it). These scripts are designed primarily for non-source distributions and are not recommended for LFS. Commands can be given to Grub from the boot loader itself. cfg" file holds the GRUB2 configuration. GRUB security features allows you to set a password to the grub entries. To change the resolution (monitor display) from the command line ( using a terminal window ) do this: ( when x is running -- don't exit Xwindows just use a terminal window. I think I successfully set the prefix and root to the extent that when I enter the command 'set' it says: prefix=(hd0,msdos5)/boot/grub root=hd0,msdos5 However,when I try the next command 'linux' it says 'unknown command'. The command we are using is still part of your Linux installation. cfg" that is intended to be used by grub2-efi, but you appear to instead be booting with plain grub2. The above command is an example, assuming the system have a backup grub configuration file under the /root/backup directory. Although you can scan and boot into most of the operating systems installed on computers such as Windows, Linux, FreeBSD and macOS from the AIO Boot's Grub2 menu. I tried vbeinfo in grub command bu mine doesn't recognize it. To test the changes, reboot the system. Log into your user account and open the terminal (Menu> Use the command line). 15 thoughts on “ Fix low resolution grub and splash screen with Nvidia drivers on Ubuntu 14. GRUB 2 has configuration files in several places. Basic commands available. Thankfully, I found a solution on a lengthy GRUB2 documentation page. It doesn't work in my Fedora 23 64-bit KDE edition. GRUB Commands. There are a lot of methods in Linux that can be used to re-install a broken grub, some can involve the ability to work and restore the boot loader by using the Linux command line and others are fairly simple and implies booting the hardware with a Linux live CD and using the GUI indications to repair the damaged boot loader. Home of the Manjaro community. If you want to install grub, under a directory other than the default "boot", you need to specify the boot directory with a command line argument to grub-install command. They are small bug-like creatures. cfg" that is intended to be used by grub2-efi, but you appear to instead be booting with plain grub2. It's called GRUB Rescue. cfg, the main configuration file. If grub-probe still fails for you, even if properly entering chroot there is one last-ditch work-around. 5 in Ubuntu 15. You can download Windows 10 from another PC. Ref : update-grub manage; Debian grub wiki. When you install Linux onto a computer, the computer's default boot sequence is bypassed or overwritten to allow Linux's Grub/Grub2 bootloader to take control of your boot sequence and run a. Run grub-mkconfig with debug spew to see details. To update Grub on operating systems that do not have an “update-grub” function, run this command in the terminal: sudo grub-mkconfig -o / boot / grub / grub. What works is to reboot using Ctrl+Alt+Del, then pressing F12 repeatedly until the normal GRUB menu appears. In a Terminal you can type one of the following to find the GRUB version: grub-install --version; grub-probe -version; The results of these commands are shown in Figure 1. GRUB gains a new command which lets users tell it not to use int13 extensions on specific devices. efi on the EFI System partition, which looks for grub. How It May Happen. It’s automatically created by running the update-grub command as root — in other words, by running sudo update-grub on Ubuntu. Commands belong to different groups. Tap Your Shoe | Cover Rhon Heramis. I recently booted Windows 10 to work with some MS Word documents and (foolishly) allowed the system to update. 04 support and a few fixes. You want to trigger that and get into grub. With BIOS, quickly press and hold the Shift key, which will bring up the GNU GRUB menu. Closest I've come so far is entering root=/dev/vda2 (even though I know its wrong), and then using blkid to see the partitions like in. Manually adding an entry for Windows 7 to an Ubuntu GRUB2 menu A recent endeavour of mine has been to set up a dual-booting arrangement on my Toshiba Equium laptop with Ubuntu 10. The Grub bootloader may only show your Linux OS as your only options to boot from. So grub> help kernel will tell you all about using the kernel command. While installing the new Grub, it will ask you to add extra kernel options. I'm hunting for a proper fix. Repairing a Broken GRUB 2 Boot-Loader on Ubuntu Posted on July 6, 2010 7:30 AM by Rob Williams When Ubuntu’s Lucid Lynx (10. June 4, 2019. In Ubuntu 10. The general format of each command is: unetbootin option="value" The quotes are unneeded when there are no spaces; for example: unetbootin distribution=Ubuntu Works fine, but for Parted Magic, you'd need:. My windows partition 0 is in hard-disk hd0, so I have the following commands: grub> rootnoverify (hd0,0) grub> makeactive grub> chainloder + 1 grub> boot. You'll be surprised, but on boot I get a command line stanza of grub. How to Bypass Grub Rescue on a Linux Computer. cfg in /boot/grub2/. Type c at the boot menu, and then give Grub the same commands that would be in the /boot/grub/grub. It will display all of the places that contains an executable available including aliases, builtins, and functions. By continuing to use Pastebin, you agree to our use of cookies as described in the Cookies Policy. The below three steps are options, it may be needed - I am not sure. Step 4: Create a text file named grub. 04 support and a few fixes. , for Debian 8 or later or Ubuntu 15. GRUB is the 3rd stage in the Linux boot process that we discussed earlier. Working of GRUB-Based Booting: 1. Those people stuck in Grub prompt can use these 4 commands to get temporary access to thier windows partition. after this I get the windows loader and then the grub menu. Rebuild GRUB with grub2-mkconfig -o /boot/grub/grub. x series with Ubuntu 16. grub" is the default parser. This obviously means that I'm using GRUB. The GRUB files for the distribution that was installed will be under a folder of the same name as the distribution. Difference Between GRUB and LILO. If entering GRUB commands interactively at the prompt, remember to enter the boot command at the end. If the value is "0", the default OS will immediately start to boot. Restart and you'll be welcomed by the familiar Grub screen. This works only in normal shell mode and not in rescue mode. So now when I turn on my computer I get a prompt that just says. Grub will show you all possible options, which in this case will be all partitions on the disk zero:. I think I need the GRUB2 commands, if they exist, in order to do so. If you want to try out a new Linux distro, be it the latest Ubuntu 11. Modifying the Linux Grub boot loader's options Posted in Linux/Unix/BSD - Last updated Apr. In the past LILO has been the most popular for Linux and the default loader on most distributions. IF YOU FOUND THIS BUG USING LENNY OR SID, THAT'S NOT IT' from `grub-pc: System unbotable due to "search --fs-uuid" command'. GRUB gains a new command which lets users tell it not to use int13 extensions on specific devices. (Once a foreign OS is booted, of course, it can be used to access any part of an unencrypted hard drive). GRUB2 (the GRand Unified Bootloader version 2) is a replacement for the original GRUB boot loader, which is now referred to as "GRUB Legacy". So the problem is with the changes made between GParted livecd 0. Thank you for your help. Discover every day !. How To: booting another Grub from Grub 1 minute read Chainloading an operating system allows grub to boot an opearating system’s boot loader. List the folders and files on the root device: ls -l / ls -l /AIO ls -l /EFI. The grub rescue> prompt comes when grub is missing. GRUB understand filesystems and can search them for files, helping you find file names and boot unfamiliar systems. It doesn't work in my Fedora 23 64-bit KDE edition. grub4dos should not be confused with grub or grub2 even though these all display the grub> prompt as the command line interpreter prompt. d/ and run update-grub to build a new grub. Set OS timeout (GRUB_TIMEOUT) By default, the selected entry from the boot menu will start to boot in 10 seconds. grub> help blocklist FILE boot. The grub2-efi package installs a prebaked grubx64. I would take care about GRUB, too, if needed. There are currently no options to prevent the command-line usage of Grub. This works only in normal shell mode and not in rescue mode. the mirroring is working fine, my only issue now is that every time I reboot the server I got the grub command line and I have manually boot using command grub> configfile (hd1,0)/grub/grub. Since you have booted from DVD, the package should be available in that. Some of the commands accept options after their name; these options should be separated from the command and other options on that line by space characters. the grub> prompt that you see when you boot from a device which has grub2 installed. So, I'm trying to run CHkDsk on my main partition due to some file corruption. Then you can use the ls command again to check the contents of each partitions to be sure. Don’t forget to update the changes made in grub file by running the following command: $ sudo update-grub 2. When I boot into Ubuntu it makes memtest the default boot menu option. grub4dos should not be confused with grub or grub2 even though these all display the grub> prompt as the command line interpreter prompt. When the CentOS boot screen appears, press ‘e’ to enter the grub options menu. The GRUB 2 command shell is just as powerful as the shell in legacy GRUB. GNU GRUB, the GRand Unified Bootloader, is intended to provide important bootloader features that are missing from typical personal computer BIOSes. Next up, use the location returned above and issue the command root(hdX, Y). GRUB2, "title" has been replaced by "menuentry". Most Linux graphical installation come with the GRUB boot menu displaying at startup. UEFI: How to repair kali-linux grub dual boot with Windows 10 If you have dual booted kali with Windows 10 then most probably you are running PC with UEFI firmware. 04 grub command prompt setup command does not exist for installing grub. The GRUB shell, although present in /boot/grub/bin/grub, is not yet supported, and some of the commands will not function on the Solaris OS due to operating system limitations in making BIOS calls. Still stuck at the grub prompt. Grub2 is a powerful boot loader and supports booting most operating systems. All I have is grub rescue. You seem to have a "grub. GRUB bietet eine Reihe nützlicher Befehle auf seiner Befehlszeilenoberfläche. Starting with RHEL 7. Note that these arguments will be added to the kernel. Xen Boot Options. Run the following commands to reset the passwords. Also, when I schedule a chkdsk it only lasts seconds instead of several minutes as it churns through my. boot (Initiate the boot, also F10 or CTRL-x). The commands following the title are the GRUB commands that will execute when that menu entry is selected. UEFI: How to repair kali-linux grub dual boot with Windows 10 If you have dual booted kali with Windows 10 then most probably you are running PC with UEFI firmware. Grub Rescue commands. If entering GRUB commands interactively at the prompt, remember to enter the boot command at the end. In Howtos reinstall grub, repair grub, restore grub, Ubuntu 13. I personally used an Ubuntu Live CD to perform all of the following steps. May 7, 2019 at 5:05 am. Grub Rescue. Some of the packages we distribute are under the GPL. 04 June 21, 2016 by Aun Grub (GRand Unified Bootloader) is the default boot loader application for most Linux/Unix systems. cfg to control the menu-driven boot process. conf file and the splash screen image file resides in the /boot partition. In fact, it gives you complete access to all filesystems on the local machine regardless of permissions or other protections. For starters, if you can see the GRUB prompt you know that the MBR is intact, and that GRUB has been properly loaded into memory. Abbreviated GRUB bootloader info for Solaris x86 This page is a very short "here's how you get it to work" thing, in true Phil style. Run the following command to reinstall grub from the live CD, replacing /dev/sdX with the device name of the hard disk above. This command only works with Arch Linux, but you can replace it with the correct. x series with Ubuntu 16. The boot command is implied and thus automatically executed at the end of each menu entry, so it does not need to be written into the menu file. To update Grub on operating systems that do not have an "update-grub" function, run this command in the terminal: sudo grub-mkconfig -o / boot / grub / grub. grub and grub2 are 'linux-like' and load their own drivers. Grub command prompt doesn’t have original Linux commands, but it is still possible to get some information if you know certain useful tricks. REPORTING BUGS Report bugs to. Next up, use the location returned above and issue the command root(hdX, Y). If the path to the grub folder (normally /boot/grub) is not correct, an unknown command or file not found message is likely. The GRUB files for the distribution that was installed will be under a folder of the same name as the distribution. If two Mint or Linux operating systems are installed, step 1 and 2 has to be done for both operating systems. List the device list, including hard disk, floppy disk, CD/DVD… ls -l. For UEFI boot only. It didn't change the order of the menu entries, but it made the asterisk appear next to the 3rd entry, Windows, so that Windows would boot by default after 10 seconds. Use the grub2-mkconfig command to generate grub. How to Reset GRUB Password in Linux This tutorial explains how to set, reset, break and remove GRUB password in RedHat and CentOS Linux step by step with practical examples. Grub 2 typically gets overridden when you install Windows or another Operating System. For menu driven interface, the configuration file like above is used. List or Check Installed Linux Kernels using command line last updated August 10, 2019 in Categories CentOS , Debian / Ubuntu , Linux , RedHat and Friends , Suse , Ubuntu Linux H ow do I list all installed kernel on Linux operating system?. lst file on its boot device. grubには、コマンド行インターフェイスで、便利な多くのコマンドが含まれています。 コマンドの中にはコマンド名の後にオプションを受け入れるものもあり、これらのオプションはスペースによって同じ行のコマンドや他のオプションと区別します。. Update grub to apply the configuration changes: sudo update-grub. To update Grub on operating systems that do not have an “update-grub” function, run this command in the terminal: sudo grub-mkconfig -o / boot / grub / grub. Super GRUB2 Disk helps you to boot into most any Operating System (OS) even if you cannot boot into it by normal means. 10 and Windows 7 on there side by side. conf configuration file. Reboot the computer. To enable pager, in GRUB command shell type: sh:grub> set pager=1 Using the command shell environment to boot operating systems grub>. Sometimes Grub fails to boot out of nowhere, sometimes it a configuration file breaks, and sometimes it refuses to load altogether. Use the ls command on the grub rescue prompt to list all the partitions. If the path to the grub folder (normally /boot/grub) is not correct, an unknown command or file not found message is likely. Certaines de ces commandes acceptent une option après leur nom. SEE ALSO grub-install(8), grub-mkrescue(1), grub-mknetdir(8) The full documentation for grub-mkimage is maintained as a Texinfo manual. All I have is grub rescue. If the GRUB pane isn't displayed, ensure that the value of the GRUB_TERMINAL line contains serial console (that is, GRUB_TERMINAL="serial console"). Adding to that, it seems certain commands just don't work. I tried vbeinfo in grub command bu mine doesn't recognize it. List the folders and files on the root device: ls -l / ls -l /AIO ls -l /EFI. Jones, a computer programmer. You can use the ls command to list devices and files. This means that the next command, chainloader , is executed without the target partition specified (as the target partition is the same, now). Enter the command "grub" to display the GRUB command line prompt where further commands will be entered: grub> Hint: If your computer is not equipped with a floppy drive, use the option "--no-floppy" when starting GRUB to skip the search for a floppy drive. It doesn't matter in which order you install Ubuntu and Android-x86 40, but if you install Android-x86 after Ubuntu, make sure you don't select to install GRUB or else you'll have to reinstall GRUB manually using a Live CD. Using GRUB rescue mode commands on CentOS The following image shows Grub’s main screen on CentOS Linux, before going to the command prompt you can check the current configuration by pressing e. The output from the find command might look like the following: (hd0,0) If more than one line is listed in the command output, you will need to decide which device you use for grub. sudo /usr/sbin/grub Then execute the following commands: grub> find /boot/grub/stage2 (will show the path of actual grub installation, you will need on the next step) grub> root (hdx,y) grub> setup (hdx) grub> quit Caution: x represents the disk number and y represents the partition number where GRUB stage2 is installed. Find the line beginning with "Linux. Commands belong to different groups. Viewing grub-mkconfig Details. Grub will show you all possible options, which in this case will be all partitions on the disk zero:. cfg as its config (configfile ${cmdpath}/grub. In the terminal window at the $ prompt, enter the command: sudo update-grub. Start by issuing the root directive as described above.