Manjaro not displaying in grub

[grahamthouard]

Manjaro is installed as a dual boot with Ubuntu and displays in GParted but does not display in grub on start-up or in grub-customizer.

[soundofthunder]

Is os-prober installed and enabled?

os-prober

In a multiboot scenario, another OS may not appear in the GRUB menu due to os-prober not being enabled. The os-prober package is responsible for detecting another OS during boot. Due to an apparent GRUB (v2.06) security recommendation, os-prober is often disabled in some distributions, or removed completely.

@Why is os-prober considered insecure?

The reasoning for this seems to be that because os-prober mounts all partitions as root (using grub-mount to check if they contain an OS), anyone sitting in your chair with a sufficient skillset can potentially exploit this to gain root privileges.

Install/Enable OS-Prober

While there is/was a valid security reason for this decision, it’s incredibly inconvenient when multibooting. Here’s how to solve the annoyance (if needed):

01. Verify that os-prober is installed; install it, if it isn’t:

# Verify os-prober is installed
pacman -Qi os-prober
# Install os-prober (if needed)
sudo pacman -S os-prober

In order for os-prober to detect another OS during boot, it needs to be enabled in /etc/default/grub, which, if you’re still reading this, it probably isn’t.

02. Check the status of os-prober;

cat /etc/default/grub | grep -i 'OS_PROBER'

# The output should include this line:
#GRUB_DISABLE_OS_PROBER=false

03. If the line is commented (#), uncomment it:

sudo nano /etc/default/grub

# UNCOMMENT this line to enable OS-Prober:
GRUB_DISABLE_OS_PROBER=false

04. Update GRUB:

sudo update-grub

On the next reboot, os-prober should function as expected and any other OS should be automatically detected and listed in the GRUB 2 menu.

I hope this helps.

Cheers.

[Aragorn]

Welcome to the forum!

@grahamthouard

grub-customizer.

Please don’t use that. It completely messes up Manjaro’s GRUB.