#!/bin/bash
set -e

function unmount() {
    local name

    for dev in "$@"; do
        name="$(cut -f1 -d' ' <<< "$dev")"

        umount "$name"
        sed -i "\\|$name|d" /tmp/automount
    done
}

readarray -t LSBLK <<< "$(lsblk --paths --list | grep -f /tmp/automount)"

while getopts a o; do
    case "$o" in
        a)
            unmount "${LSBLK[@]}"
            exit 0
            ;;
        *)
            ;;
    esac
done

select dev in "${LSBLK[@]}"; do
    unmount "$dev"
done