ddrescue recovery script

recover.sh

#!/bin/bash

function exit_with_usage() {
    # usage: exit_with_usage

    echo "Usage: ${0##*/} <src> <dest>" >&2
    exit 1
}

function prompt() {
    # usage: prompt "prompt message"

    local message="$1"
    local response

    while [[ -z "${response}" ]]; do
        read -p "${message} [y/n] " response

        if [[ "${response}" =~ ^[yY]$ ]]; then
            printf "\n"
            return 0
        elif [[ "${response}" =~ ^[nN]$ ]]; then
            return 1
        else
            unset response
        fi
    done
}

function pprint_hdparm() {
    # usage: pprint_hdparm "device"

    local device="$1"
    local pattern='Model\ Number
                   |Serial\ Number
                   |Firmware\ Revision
                   |(Logical|Physical).*Sector\ size
                   |device\ size\ with\ M'

    hdparm -I "${device}" | egrep "${pattern}"
}

function main() {
    if [[ "$#" -ne 2 ]]; then
        exit_with_usage
    fi

    local src="$1"
    local dest="$2"

    # Prevent Seagates from getting clobbered
    local dest_model=$(hdparm -I "${dest}" \
                       | awk -F: '/Model\ / { gsub(/^\ +/, "", $2);
                                              print $2; }')
    local pattern='^ST'

    if [[ "${dest_model}" =~ ${pattern} ]]; then
        exit_with_error "Refusing to overwrite ${dest}"
    fi

    # Source
    echo 'Source: '
    pprint_hdparm "${src}"

    # Destination
    echo 'Destination: '
    pprint_hdparm "${dest}"

    prompt 'Continue?' || exit $?

    local serial=$(hdparm -I "${src}" \
                   | awk -F: '/Serial\ Number/ { gsub(/ /, "");
                                                 print $2; }')

    local bs=$(hdparm -I "${src}" \
               | awk -F: '/Physical.*Sector\ size/ { gsub(/bytes/, "");
                                                     gsub(/ /, "");
                                                     print $2; }')

    # First backup all error-free areas
    ddrescue                  \
        --block-size="${bs}"  \
        --force               \
        --no-split            \
        "${src}" "${dest}"    \
        "${serial}".log

    # Then try to recover any bad sectors
    ddrescue                  \
        --block-size="${bs}"  \
        --direct              \
        --force               \
        --max-retries=3       \
        "${src}" "${dest}"    \
        "${serial}".log

    # Last, retrim?
    # ddrescue --retrim --complete-only
}

main "$@"