recover-bootloader

#!/bin/bash

function enter-to-continue() {
    echo &&
    read -r -p "Press ENTER to continue..." &&
    echo &&
    echo
}

function yn-y() {
    # Y is the default
    local REPLY
    read -p "${1} [Y/n] " -r
    if [[ $REPLY =~ ^[Nn]$ ]]; then
        return 1
    else
        return 0
    fi
}

function yn-n() {
    # N is the default
    local REPLY
    read -p "${1} [y/N] " -r
    if [[ $REPLY =~ ^[Yy]$ ]]; then
        return 0
    else
        return 1
    fi
}

function read-existing-path() {
    read -r -p "${1}: " name || fail
    if [ -z "${name}" ] || [ ! -e "${name}" ]; then
        echo "That file doesn't exist!" 1>&2
        exit 1
    else
        echo "${name}"
    fi
}

function fail() {
    echo -e "\e[31mSomething went wrong!\e[0m"
    exit 1
}


cat <<EOF
This script will reinstall the bootloader from the Linux Mint 18, 18.1
or 18.2 installer live USB, if for some reason you can no longer boot
your installed system (make sure you use the Live USB that matches the
version of the installed system).
EOF

if ! yn-n "Continue?"; then
    exit 0
fi


# Not completely foolproof, but should do the job...
if ! lsb_release -a 2>/dev/null | grep 'sarah\|serena\|sonya' &>/dev/null || ! type ubiquity &>/dev/null; then
cat <<EOF


You are not running on the Linux Mint 18, 18.1 or 18.2 installer live
USB. Cannot go any further.
EOF
    exit 1
fi


if [ -e '/sys/firmware/efi' ]; then
    FIRMWARE='uefi'
else
    FIRMWARE='bios'
fi

cat <<EOF


Your firmware is '${FIRMWARE}'. If that doesn't sound right (i.e. you
wanted to boot in UEFI mode but booted in BIOS mode instead), type 'n'
at the prompt and reboot in the correct mode.

EOF

if ! yn-y "Is the firmware mode correct?"; then
    exit 0
fi

echo &&
CRYPTPART="$(read-existing-path "Enter the name of the physical partition where your encrypted container is located; typically something like /dev/sda1, /dev/sda2, /dev/nvme0n1p2, etc.")" &&
echo &&


sudo cryptsetup open "${CRYPTPART}" "$(basename "${CRYPTPART}")_crypt" &&


echo &&
ROOTDEV="$(read-existing-path "Enter the path of the device where your root partition is located; using the example names from the installation script, this would be /dev/mapper/mint-root, but of course yours might be different.")" &&
echo &&
# shellcheck disable=SC2015
BOOTLOADER="$(read-existing-path "Enter the device on which the bootloader is installed; typically something like /dev/sda or /dev/sdb for hard drives, or /dev/nvme0n1 or /dev/nvme0n2 for NVME SSDs")" || fail

if [ "${FIRMWARE}" = 'uefi' ]; then
    read -r -p "Enter the number of the UEFI boot partition, e.g. if the partition is /dev/sda1 on a hard drive, enter 1, or /dev/nvme0n1p2 on an NVME SSD, enter 2: " UEFINUMBER || fail
    if [ -z "${UEFINUMBER}" ]; then
        echo 'Invalid partition number'
        fail
    fi
fi


sudo mount "${ROOTDEV}" /mnt &&
sudo mount --bind /dev /mnt/dev &&
sudo mount --bind /dev/pts /mnt/dev/pts &&
sudo mount --bind /sys /mnt/sys &&
sudo mount --bind /proc /mnt/proc &&
# shellcheck disable=SC2015
sudo mount --bind /run /mnt/run || fail

if [ "${FIRMWARE}" = 'uefi' ]; then
    sudo mount "${BOOTLOADER}${UEFINUMBER}" /mnt/boot/efi || fail
fi


sudo chroot /mnt locale-gen --purge --no-archive &&
# shellcheck disable=SC2015
sudo chroot /mnt update-initramfs -u || fail




if [ "${FIRMWARE}" = 'bios' ]; then
    sudo chroot /mnt update-grub &&
    sudo chroot /mnt grub-mkconfig -o /boot/grub/grub.cfg &&
    # shellcheck disable=SC2015
    sudo chroot /mnt grub-install "${BOOTLOADER}" || fail
elif [ "${FIRMWARE}" = 'uefi' ]; then
    sudo chroot /mnt update-grub &&
    sudo mkdir -p /mnt/boot/efi/EFI/mint &&
    sudo chroot /mnt grub-mkconfig -o /boot/efi/EFI/mint/grub.cfg &&
    echo "configfile \${cmdpath}/grub.cfg" | sudo tee /mnt/tmp/grub.cfg &>/dev/null &&
    sudo chroot /mnt grub-mkstandalone -d /usr/lib/grub/x86_64-efi/ -O x86_64-efi --compress="xz" --modules="part_gpt part_msdos crypto cryptodisk luks disk diskfilter lvm" --fonts="unicode" -o "/boot/efi/EFI/mint/grubx64.efi"  "boot/grub/grub.cfg=/tmp/grub.cfg" -v &&
    # shellcheck disable=SC2015
    sudo chroot /mnt efibootmgr -c -d "${BOOTLOADER}" -p "${UEFINUMBER}" -L "Mint" -l "\EFI\mint\grubx64.efi" || fail
else
    # Should never get here
    fail
fi

if [ "${FIRMWARE}" = 'uefi' ]; then
    sudo umount /mnt/boot/efi || fail
fi

sudo umount /mnt/proc /mnt/dev/pts /mnt/dev /mnt/sys /mnt/run /mnt &&


echo 'Finished'