GRUB Configuration

GRUB Installation link

Firstly, let’s check if we have already installed GRUB:

  ls /boot/EFI/GRUB
# or ls /boot/efi/EFI/GRUB
  

you should see files like grubx64.efi or similar. This means GRUB have been installed successfully.

This means we should also have the grub.cfg config file; you can check using:

  cat /boot/grub/grub.cfg
  

Add Windows Entry (only if you created a new EFI partition) link

If you created a new EFI partition in pre-Installation phase, you will probably need to add windows manually. Before doing this we can try to make GRUB detect other operating systems if the tool os-prober is installed and enabled:

  paru -S os-prober # or use `sudo pacman`
sudo grub-mkconfig -o /boot/grub/grub.cfg
  

Then check if grub managed to add it:

  cat /boot/grub/grub.cfg | grep windows
  

If this does not work, then we have to add Windows manually.

1. Identify the Windows EFI Partition

   Firstly we have to identify which one is the Windows EFI Partition and note its UUID. To do that you can simply use:

     sudo blkid | grep -i efi
     

   you should see something like /dev/nvme1n1p1 with partition label ‘EFI system partition’. If not,

   Note its UUID (a string like XXXX-XXXX).

2. Edit the GRUB Custom file

   Let’s open now the GRUB Custom file with root privileges:

     sudo nano /etc/grub.d/40_custom
     

   At the end of the file, add a new menu entry for Windows (make sure to replace XXXX-XXXX with the right UID):

     menuentry "Windows 10" --class windows {
       insmod part_gpt
       insmod fat
       search --fs-uuid --no-floppy --set=root XXXX-XXXX
       chainloader /EFI/Microsoft/Boot/bootmgfw.efi
   }
     

3. Reorder the Entries (Optional)

   The order of the GRUB entries depends on the name of the files in /etc/grub.d/ folder.

   Let’s check the current situation:

     $ ls /etc/grub.d/
   # You should see something like this:
   00_header 10_linux 20_linux_xen 25_bli 30_0s_prober 30_wefi firmware 40_custom 41_custom README
     

   To reorder the entries is sufficient to rename those files. Let’s rename now the file we have modified in the previous step:

     rename /etc/grub.d/40_custom /etc/grub.d/25_windows /etc/grub.d/40_custom
     

4. Timeout and Default boot option

   We can define a timeout before GRUB automatically boots from the default option. To do that we shell modify the /etc/default/grub file:

     sudo nano /etc/default/grub 
     

   and modify the following variables:

     GRUB_DEFAULT=saved      # default entry is the last selection
   GRUB_TIMEOUT=5          # 5 second timeout
   # ...
   GRUB_SAVEDEFAULT=true   # needed to make GRUB remember the last option
     

5. Regenerate the GRUB Configuration file and Reboot

   Now, let’s generate the GRUB configuration file and then reboot to see if everything works as expected:

     sudo grub-mkconfig -o /boot/grub/grub.cfg
   reboot
     

Set GRUB Theme link

To customize GRUB we can create a theme from zero or use an existing one. There are many repositories where you can find a lot of themes of all types. Here I found a well-structured repo:

settings_account_box

I personally choose the Arcade theme, this is the result:

I also disabled submenus setting GRUB_DISABLE_SUBMENU=true in /etc/default/grub and modified /etc/grub.d/10_linux to rename the entries, but this is not recommended.

To use a theme just clone the theme repository:

  git clone url/to/theme
  

Some themes are stored in folders of a larger repo. Find the theme directory and copy it in /boot/grub/themes (you will need root priviledges):

  sudo cp -r path/to/theme /boot/grub/themes/THEME_NAME
  

Then, inside /etc/default/grub let’s se the GRUB_THEME:

  GRUB_THEME=/boot/grub/themes/THEME_NAMEtheme.txt
  

Save and exit. Then, once again, let’s regenerate the GRUB configuration file and then reboot:

  sudo grub-mkconfig -o /boot/grub/grub.cfg
reboot