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