update-bootloader

#!/bin/bash

SETTINGS_DIR="${HOME}/.mint-encrypted-install"

function load-setting() {
    # Returns empty string if file does not exist
    cat "${SETTINGS_DIR}/${1}" 2>/dev/null
}

function save-setting() {
    # shellcheck disable=SC2015
    mkdir -p "${SETTINGS_DIR}" &&
    echo "${2}" > "${SETTINGS_DIR}/${1}" || fail
}

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 update the initramfs and bootloader, from inside a
running Mint installation previously set up using
mint-encrypted-install.
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 an installed Linux Mint 18, 18.1 or 18.2 system.
Cannot go any further.
EOF
    exit 1
fi


# Convenient place to get the sudo password, before asking for settings
sudo true || fail
echo


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


# Load settings
BOOT_DEVICE="$(load-setting boot-device)"

if [ "${FIRMWARE}" = 'uefi' ]; then
    UEFI_PARTITION_NUM="$(load-setting uefi-partition-num)"
    UEFI_BOOT_ENTRY="$(load-setting uefi-boot-entry)"
fi


# Check settings
if [ ! -z "${BOOT_DEVICE}" ]; then
    echo 'Block devices:'
    lsblk
    cat <<EOF

Settings saved from last run:
    Bootloader device: ${BOOT_DEVICE}
EOF
    if ! yn-y '    Is this correct?'; then
        BOOT_DEVICE=''
    fi
    echo
fi

if [ "${FIRMWARE}" = 'uefi' ]; then
     if [ ! -z "${UEFI_PARTITION_NUM}" ]; then
         cat <<EOF
    UEFI partition number on boot device: ${UEFI_PARTITION_NUM}
EOF
         if ! yn-y '    Is this correct?'; then
             UEFI_PARTITION_NUM=''
         fi
         echo
     fi

     if [ ! -z "${UEFI_BOOT_ENTRY}" ]; then
         cat <<EOF
Valid options for UEFI boot entry are any of the four-digit hex
numbers listed below:

EOF
         sudo efibootmgr
         echo
         cat <<EOF
    UEFI boot entry: ${UEFI_BOOT_ENTRY}

EOF
         if ! yn-n '    Is this correct?'; then
             UEFI_BOOT_ENTRY=''
         fi
         echo
     fi
fi


# Get any missing settings
if [ -z "${BOOT_DEVICE}" ]; then
    echo 'Block devices:'
    lsblk
    echo
    BOOT_DEVICE="$(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")"
    if [ -z "${BOOT_DEVICE}" ]; then
        fail
    fi
    save-setting boot-device "${BOOT_DEVICE}"
    echo
fi

if [ "${FIRMWARE}" = 'uefi' ]; then
    if [ -z "${UEFI_PARTITION_NUM}" ]; then
        echo 'Block devices:'
        lsblk
        echo
        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: " UEFI_PARTITION_NUM || fail
        if [ -z "${UEFI_PARTITION_NUM}" ]; then
            echo 'Invalid partition number'
            fail
        fi
        save-setting uefi-partition-num "${UEFI_PARTITION_NUM}"
        echo
    fi

    if [ -z "${UEFI_BOOT_ENTRY}" ]; then
        echo "Existing boot entries are:"
        echo
        sudo efibootmgr
        echo
        read -r -p "Enter the four-digit hex number of an existing boot entry to update it, or leave this blank to create a new one: " UEFI_BOOT_ENTRY || fail
        save-setting uefi-boot-entry "${UEFI_BOOT_ENTRY}"
        echo
    fi
fi


# Now actually start the update
sudo locale-gen --purge --no-archive &&
# shellcheck disable=SC2015
sudo update-initramfs -u || fail


if [ "${FIRMWARE}" = 'bios' ]; then
    sudo update-grub &&
    sudo grub-mkconfig -o /boot/grub/grub.cfg &&
    # shellcheck disable=SC2015
    sudo grub-install "${BOOT_DEVICE}" || fail
elif [ "${FIRMWARE}" = 'uefi' ]; then
    sudo update-grub &&
    sudo mkdir -p /boot/efi/EFI/mint &&
    sudo grub-mkconfig -o /boot/efi/EFI/mint/grub.cfg &&
    echo "configfile \${cmdpath}/grub.cfg" | sudo tee /tmp/grub.cfg &>/dev/null &&
    # shellcheck disable=SC2015
    sudo 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 || fail

    echo
    if [ -z "${UEFI_BOOT_ENTRY}" ]; then
        # Create a new boot entry
        sudo efibootmgr -c -d "${BOOT_DEVICE}" -p "${UEFI_PARTITION_NUM}" -L "Mint" -l "\EFI\mint\grubx64.efi" || fail
    else
        # Update an existing boot entry
        sudo efibootmgr -b "${UEFI_BOOT_ENTRY}" -d "${BOOT_DEVICE}" -p "${UEFI_PARTITION_NUM}" -L "Mint" -l "\EFI\mint\grubx64.efi" || fail
    fi
else
    # Should never get here
    fail
fi

cat <<EOF

Finished - you may want to change the boot order using 'efibootmgr -o',
and remember to run this script again if you update grub or the kernel.
EOF