View source for GRUB/Restore the GRUB Bootloader

= Overview =

As with any Linux operating system, the GRUB ('''GR'''and '''U'''nified '''B'''ootloader) is responsible for booting up Manjaro. If for any reason your GRUB is not working --perhaps due to being corrupted, mis-configured, or even deleted-- then it may not be necessary to reinstall Manjaro. '''The GRUB can instead be fully repaired and restored, retaining your installed Manjaro system'''. To undertake this task, you will need to use your Manjaro installation media, such as, a CD/DVD or USB Flashdrive.

= Boot the Manjaro Installation Media =

'''1.''' Insert and boot your Manjaro installation media. 

'''2.''' Select your '''preferred language''' (F2) and '''keyboard layout''' (F3).

{{tip|Setting the language and keyboard layout are undertaken by pressing the ''Function'' (F) keys. As many computers have multiple functions assigned to each function key, it may be necessary to hold down another key first to use them. For example, on a HP G62 laptop, to use the function keys, the 'fn' key must first be pressed and held.}}


'''3.''' Boot Manjaro Linux. It does not matter which boot option you choose, as the installation media is being used solely to repair/reinstate the GRUB, and not to install a fresh system.

'''4.''' Open the terminal or access the command line of the live CD. 

* '''From the desktop environment''': open a terminal from your desktop menu, and enter ''sudo su'' in the terminal.
  or
* '''From the command line''' of the NET-Edition or having used the ''Boot in Text mode'' option: enter the default login username ''root'' and then the password "manjaro" to log in.

= Identify and Prepare the Installed Partition(s) =

{{note|The procedure given below may also be described as [https://wiki.archlinux.org/index.php/Change_Root chroot](ing).}}


'''1.''' Ensure that you are using the Root account, which is identified by a hash ('#') at the beginning of the command line, rather than a dollar ('$'). To switch to Root, enter the command:

 sudo su

'''2.''' List your partitions. This is necessary in order to identify the partition your Manjaro system is installed on. If you have used a separate boot partition, it will be necessary to identify this as well. For a list of your paritions, enter the command:

 lsblk -f

   or

 sudo blkid -o list -c /dev/nul


In this particular instance, '''having used the assisted preparation method to install Manjaro earlier''', the partitions for the author's Manjaro system are as follows:

* '''/dev/sda1''': Boot partition
* '''/dev/sda2''': Swap partition
* '''/dev/sda3''': Manjaro system
* '''/dev/sda4''': Space for personal files.


If you are still unsure, then you can also use an application called ''gparted'', which should be in Menu > System > GPartEd. This will provide a simple visual illustration of the partitions on your hard drive(s). If a separate partition for the GRUB exists, it will be marked as 'bootable', and should only be about 100MB in size.


'''3.''' Mount your Manjaro system partition. The syntax to mount the Manjaro system partition is:

 mount /dev/'''[partition used for Manjaro system]''' /mnt


In this instance, as the Manjaro system partition is ''/dev/sda3'', this will be mounted using the following command:

 mount /dev/'''sda3''' /mnt


'''IF''' you have used a separate partition for your GRUB bootloader, then this must also be mounted. The syntax to mount a separate partition used to boot is:

 mount /dev/'''[partition used for GRUB]''' /mnt/boot


In this instance, a separate partition --''/dev/sda1''-- has been used for the GRUB, and will be mounted using the following command:

 mount /dev/'''sda1''' /mnt/boot

{{note|Again, if you have not used a separate boot partition, then it (obviously) does not need to be mounted!}}


'''3.''' Change to the root directory of your mounted partitions. 

 cd /mnt

This is undertaken so that you are working from  --and with-- your installed system, rather than the installation media. To do so, it will be necessary to enter a series of commands in the following order:

 mount -t proc proc /mnt/proc
 mount -t sysfs sys /mnt/sys
 mount -o bind /dev /mnt/dev
 mount -t devpts pts /mnt/dev/pts/
 chroot /mnt


'''4.''' Install the software applications ''mtools'' and ''os-prober''. mtools is a collection of tools to access MS-DOS disks from GNU/Linux and Unix without mounting them. os-prober is a utility that detects if there are any other operating systems present. Install them both with the following command:

 pacman -S mtools os-prober

= Restore GRUB =

== For BIOS Systems ==

'''1.''' Install a new GRUB bootloader with the following command:

 grub-install /dev/sda
{{Note|sda is the disk device where you want to install GRUB. You can check it using ''lsblk -f'' or using GParted as explained before.}}


'''2.''' Recheck to ensure the that installation has completed without any errors:

 grub-install --recheck /dev/sda


'''3.''' Finally, configure the freshly installed GRUB bootloader:

 update-grub


All done! Now close the terminal and reboot your system to use your freshly re-installed GRUB.

== For UEFI Systems ==

{{Warning|You need to be [https://wiki.archlinux.org/index.php/Change_Root chrooted] for this procedure as mentioned in the [[Restore_the_GRUB_Bootloader#Identify_and_Prepare_the_Installed_Partition.28s.29 | previous step.]]}}


1.) First of all check the partition for the ESP (EFI System Partition). An ESP is a fat32 partition and contains .efi files for booting.

It can be checked using Gparted or from the terminal using ''fdisk -l''


('''Note:'''
''If you do not have a EFI partition'', you will need to create it.
Use Gparted for that.

Type- ''fat32''

Size- ''512 mb to 1 gb'')


2.) Create the ''/boot/efi'' directory
 sudo mkdir /boot/efi


3.) Mount the EFI partition as ''/boot/efi''
 sudo mount /dev/sdXY /boot/efi
X = Alphabet of the drive = a,b,c ...
Y = Partition number of the EFI partition = 1,2,3,4...

Example - ''/dev/sda4''


4.) Re-install Grub.
 sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=manjaro --recheck


5.) Update Grub configuration file.
 sudo update-grub

=== Note ===

If you get something like

 EFI variables are not supported on this system.

Then install the {{ic|efibootmgr}}, {{ic|dosfstools}} and {{ic|grub}} packages and try steps 4 and 5 again.

If it still doesn't work, then try exiting the chroot environnment by typing '''exit''', then loading the '''efivars''' module:
 sudo modprobe efivars

and retry the steps again. Should the modprobe fail try 
 sudo modprobe efivarfs
and in the chroot
 mount -t efivarfs efivarfs /sys/firmware/efi/efivars


And if you get something like

 grub-install: error: failed to get canonical path of `union'.

means that probably you forgot to [[Restore_the_GRUB_Bootloader#Identify_and_Prepare_the_Installed_Partition.28s.29 | chroot]].

'''See also'''

[http://wiki.manjaro.org/index.php?title=UEFI_-_Install_Guide UEFI Install Guide]

[https://wiki.archlinux.org/index.php/GRUB#UEFI_systems_2 Arch Wiki:GRUB#UEFI_systems_2]

=== Alternative method ===

Mount the ext4 Manjaro root partition at {{ic|/install}}

Mount the vfat Manjaro efi partition at {{ic|/install/boot/efi}}

And then install Grub as:

 grub-install --target=x86_64-efi --efi-directory=/install/boot/efi --bootloader-id=manjaro --boot-directory=/install/boot --recheck --debug

After the above you could chroot and try the '''update-grub''' command as earlier.

=Support=


Post for support at the forums- [http://forum.manjaro.org/index.php?board=3.0]

=See Also=

[https://forum.manjaro.org/index.php?topic=7552.0 Forum topic]

[https://wiki.archlinux.org/index.php/GRUB The Arch Wiki]


[[Category:Contents Page]]

= Troubleshooting =

=== Arch Linux is not recognized ===
If Arch Linux wasn't recognized after an update-grub then probably your Arch installation is missing the package lsb-release.


= See also =

[https://wiki.archlinux.org/index.php/GRUB GRUB: Arch Wiki]


[[Category:Contents Page]]