Script to easily and safely remove a specific version of Linux kernel files in /boot and its modules in /lib/modules

kernel_uninstaller.sh

#!/bin/bash

usage() {
  echo "Usage: $0 [--apply]"
  echo "Default is dry-run mode. Use --apply to actually delete files and directories."
  exit 1
}

if [ "$EUID" -ne 0 ]; then
  echo "You must run this script as root."
  exit 1
fi


# Dry-run as default
apply_changes=0

if [ "$1" == "--apply" ]; then
  apply_changes=1
elif [ "$1" != "" ]; then
  usage
fi

# Fetch current symbolic links
current_vmlinuz=$(readlink -f /boot/vmlinuz)
current_vmlinuz_old=$(readlink -f /boot/vmlinuz.old)
current_config=$(readlink -f /boot/config)
current_config_old=$(readlink -f /boot/config.old)
current_initrd=$(readlink -f /boot/initrd.img)
current_initrd_old=$(readlink -f /boot/initrd.img.old)
current_system_map=$(readlink -f /boot/System.map)
current_system_map_old=$(readlink -f /boot/System.map.old)

# Fetch kernel lists
kernels=($(ls /boot/vmlinuz-* | xargs -n 1 basename))
echo "Available kernels:"
for i in "${!kernels[@]}"; do
  echo "$i) ${kernels[$i]}"
done

# Input
echo "Enter the kernel numbers to delete (space-separated):"
read -a delete_indices

delete_files=()
delete_dirs=()

for index in "${delete_indices[@]}"; do
  kernel="${kernels[$index]}"
  
  # Set related files
  vmlinuz_file="/boot/$kernel"
  config_file="/boot/config-${kernel#vmlinuz-}"
  initrd_file="/boot/initrd.img-${kernel#vmlinuz-}"
  system_map_file="/boot/System.map-${kernel#vmlinuz-}"
  modules_dir="/lib/modules/${kernel#vmlinuz-}"

  # For safety, do not delete if the selected kernel is symlinked to vmlinuz and initrd
  if [[ "$vmlinuz_file" == "$current_vmlinuz" || "$vmlinuz_file" == "$current_vmlinuz_old" ]]; then
    echo "Skipping $vmlinuz_file (linked to vmlinuz or vmlinuz.old)"
  else
    delete_files+=("$vmlinuz_file")
  fi

  if [[ "$config_file" == "$current_config" || "$config_file" == "$current_config_old" ]]; then
    echo "Skipping $config_file (linked to config or config.old)"
  else
    delete_files+=("$config_file")
  fi

  if [[ "$initrd_file" == "$current_initrd" || "$initrd_file" == "$current_initrd_old" ]]; then
    echo "Skipping $initrd_file (linked to initrd.img or initrd.img.old)"
  else
    delete_files+=("$initrd_file")
  fi

  if [[ "$system_map_file" == "$current_system_map" || "$system_map_file" == "$current_system_map_old" ]]; then
    echo "Skipping $system_map_file (linked to System.map or System.map.old)"
  else
    delete_files+=("$system_map_file")
  fi

  if [ -d "$modules_dir" ]; then
    if [[ "$vmlinuz_file" == "$current_vmlinuz" || "$vmlinuz_file" == "$current_vmlinuz_old" ]]; then
      echo "Skipping $modules_dir (linked kernel in use)"
    else
      delete_dirs+=("$modules_dir")
    fi
  else
    echo "Skipping $modules_dir (directory not found)"
  fi
done

# Print targets
echo ""
echo "Files to delete:"
for file in "${delete_files[@]}"; do
  echo "$file"
done

echo ""
echo "Directories to delete:"
for dir in "${delete_dirs[@]}"; do
  echo "$dir"
done

# Apply
if [ $apply_changes -eq 1 ]; then
  echo "Deleting files and directories..."
  for file in "${delete_files[@]}"; do
    if [ -f "$file" ]; then
      sudo rm -f "$file"
      echo "Deleted $file"
    else
      echo "File not found: $file"
    fi
  done

  for dir in "${delete_dirs[@]}"; do
    if [ -d "$dir" ]; then
      sudo rm -rf "$dir"
      echo "Deleted directory $dir"
    else
      echo "Directory not found: $dir"
    fi
  done
  echo "Deletion completed."
  sudo update-grub
else
  echo ""
  echo "Dry-run mode: No files or directories were deleted. Use --apply to delete them."
fi