A simple Grub Restore script to Restore Debian based system for UEFI based systems

README.md

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+
+# 🛠️ GRUB EFI Repair Script
+
+If you run Windows on Dual Boot with Linux, you may have faced issues like your windows partition overwrites the linux boot loader forcing user to log in on windows.
+
+This script was created to solve that issue in UEFI based Linux systems.
+
+A simple Bash script to reinstall GRUB on UEFI-based Linux systems and set the correct boot order.
+
+---
+
+## ⚠️ Requirements & Conditions
+
+Before running this script, ensure your system meets **all** of the following conditions.
+
+### **1. UEFI System Required**
+
+This script works **only on UEFI systems**.
+Legacy BIOS systems are **not supported**.
+
+It uses:
+
+```
+grub-install --target=x86_64-efi
+```
+
+---
+
+### **2. EFI Partition Must Be Mounted at `/boot/efi`**
+
+Your system must have an EFI System Partition (ESP) mounted at:
+
+```
+/boot/efi
+```
+
+The script expects this directory to exist:
+
+```
+/boot/efi/EFI
+```
+
+If your distribution uses a different mount point (such as `/efi` or `/boot`), adjust the script accordingly.
+
+---
+
+### **3. GRUB Must Be Installed and Used**
+
+This script only works with **GRUB**.
+
+It does **NOT** support:
+
+* systemd-boot
+* rEFInd
+* LILO
+* vendor-specific boot managers
+
+Running it on these setups will result in errors.
+
+---
+
+### **4. `update-grub` Must Exist**
+
+The script uses:
+
+```
+update-grub
+```
+
+This command is available only on **Debian-based** systems:
+
+* Debian
+* Ubuntu
+* Linux Mint
+* Kali
+* MX Linux
+
+It will **not** work on:
+
+* Fedora / RHEL / CentOS / Rocky / AlmaLinux
+* Arch Linux / Manjaro
+* OpenSUSE
+
+Those use `grub2-mkconfig`.
+
+---
+
+### **5. Bootloader ID Defaults to “Debian”**
+
+The GRUB installation uses:
+
+```
+--bootloader-id=Debian
+```
+
+Different distros use different EFI bootloader IDs:
+
+* Ubuntu → `ubuntu`
+* Fedora → `fedora`
+* Linux Mint → `LinuxMint`
+* Arch Linux → `arch`
+
+Update this value if needed.
+
+---
+
+### **6. Requires `efibootmgr` Support**
+
+The script modifies UEFI boot order using:
+
+```
+efibootmgr -o
+```
+
+This requires:
+
+* Firmware that allows BootOrder modification
+* Root access
+
+Some cloud/VPS providers restrict this capability.
+
+---
+
+### **7. Must Be Run as Root**
+
+You must run the script with `sudo` or as root because it executes privileged commands:
+
+* `grub-install`
+* `update-grub`
+* `efibootmgr`
+
+---
+
+### **8. Multi-Boot Systems**
+
+If multiple OSes are installed (e.g., Windows + Linux), this script will set **Debian GRUB as the first boot entry**, overriding others.
+
+---
+
+### **9. Risk Warning**
+
+Changing GRUB/EFI settings can make a system unbootable if misconfigured.
+
+Recommended:
+
+* Keep a bootable USB handy
+* Confirm your EFI mount point
+* Back up important data
+
+---
+
+## 📜 Usage
+
+Make the script executable:
+
+```
+chmod +x grub-fix.sh
+```
+
+Run the script:
+
+```
+sudo ./grub-fix.sh
+```
+
+Reboot when done.
+
+---
+
+## ✔ What the Script Does
+
+1. Verifies EFI directory presence
+2. Lists available EFI boot entries
+3. Reinstalls GRUB to the EFI System Partition
+4. Updates GRUB configuration
+5. Detects the Debian boot entry
+6. Sets Debian as the first boot option
+7. Completes cleanly
+
+---
+
+## 📌 Notes
+
+This script is designed for **Debian-based Linux systems** with a standard EFI layout.
+It is **not guaranteed to work on all Linux distributions**.
+
+---
+
+

restore-grub.sh

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+#!/bin/bash
+
+set -e
+
+echo "=== Checking EFI directories ==="
+ls /boot/efi/EFI || { echo "EFI partition not mounted!"; exit 1; }
+
+echo "EFI entries found:"
+ls /boot/efi/EFI/
+
+echo "=== Reinstalling GRUB to EFI partition ==="
+sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=Debian
+
+echo "=== Updating GRUB ==="
+sudo update-grub
+
+echo "=== Fixing boot order (setting Debian to first) ==="
+# Find Debian boot entry number
+DEBIAN_BOOTNUM=$(sudo efibootmgr | grep -i debian | grep -oP 'Boot\K[0-9A-Fa-f]{4}')
+
+if [ -z "$DEBIAN_BOOTNUM" ]; then
+    echo "Error: Could not find Debian entry in efibootmgr!"
+    sudo efibootmgr
+    exit 1
+fi
+
+echo "Found Debian entry: Boot$DEBIAN_BOOTNUM"
+echo "Setting Debian as first boot option..."
+
+sudo efibootmgr -o $DEBIAN_BOOTNUM
+
+echo "=== Done! ==="
+echo "Reboot your system and GRUB should load first."
+