My backup system

#!/bin/bash
#
# backup.sh
#
# Copyright (C)  2019  Franco Masotti <franco.masotti@live.com>.
# Permission is granted to copy, distribute and/or modify this document
# under the terms of the GNU Free Documentation License, Version 1.3
# or any later version published by the Free Software Foundation;
# with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
# A copy of the license is included in the section entitled "GNU
# Free Documentation License".

declare -A BACKUP_ALIAS

# Get correct path before loading the configuration file.
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
. ""${DIR}"/backup.conf"

SRC="${1}"
DST="${2}"

{ command -V rsync && command -V bash && command -V mail \
    && command -V printf && command -V sync; } \
    || exit 1
{ [ -z "${SRC}" ] || [ -z "${DST}" ]; } \
    && printf "%s\n" 'check inputs' 2>&1 && exit 1
[ ${UID} -ne 0 ] && printf "%s\n" 'user must be root' 2>&1 && exit 1

START=$(date +%s)
if [ "${SRC}" = '/*' ]; then
    # Use the exclude option to avoid infinite loops due to symlinks and to
    # avoid backing up the /data mountpoint itself.
     rsync --archive --acls --xattrs --hard-links --delete /* "${DST}" --exclude={/dev/*,/proc/*,/sys/*,/tmp/*,/run/*,/mnt/*,/media/*,/lost+found,/data}
elif [ "${SRC}" = '/data/*' ]; then
    rsync --archive --acls --xattrs --hard-links --delete /data/* "${DST}"
else
    rsync --archive --acls --xattrs --hard-links --delete "${SRC}" "${DST}"
fi

ret_rsync=${?}
# Flush data.
sync

FINISH=$(date +%s)
if [ ${ret_rsync} -eq 0 ]; then
    if [ "${LOG_TO_FILE}" = 'true' ]; then
        printf "%s\n" "[$(date '+%Y-%m-%d, %T') OK backup_ext_disks] "${DST}" ; \
$((${FINISH}-${START}))s" >> "${LOG_FILE}"
    fi
    if [ "${LOG_TO_EMAIL}" = 'true' ]; then
        printf "%s\n" "Backup on "${BACKUP_ALIAS["${DST}"]}" took $((${FINISH}-${START}))s" \
            | mail -r "${EMAIL_SENDER}" -s 'Backup complete' "${EMAIL_RECIPIENT}"
    fi
else
    if [ "${LOG_TO_FILE}" = 'true' ]; then
        printf "%s\n" "[$(date '+%Y-%m-%d, %T') FAILED backup_ext_disks \
ret_rsync=${ret_rsync}] "${DST}"" \
        >> /var/log/rsync.log
    fi
    if [ "${LOG_TO_EMAIL}" = 'true' ]; then
        printf "%s\n" "Backup error on "${BACKUP_ALIAS["${DST}"]}". Error code ${ret_rsync}" \
            | mail -r "${EMAIL_SENDER}" -s 'Backup error' "${EMAIL_RECIPIENT}"
    fi
fi

#
# backup.conf
#
# Copyright (C)  2019  Franco Masotti <franco.masotti@live.com>.
# Permission is granted to copy, distribute and/or modify this document
# under the terms of the GNU Free Documentation License, Version 1.3
# or any later version published by the Free Software Foundation;
# with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
# A copy of the license is included in the section entitled "GNU
# Free Documentation License".

# Friendlier names used in logs and emails.
BACKUP_ALIAS['/mnt/backup_root']='backup-root'
BACKUP_ALIAS['/mnt/backup_root_enc']='backup-root-encrypted'
BACKUP_ALIAS['/mnt/backup_data']='backup-data'
BACKUP_ALIAS['/mnt/backup_data_enc']='backup-data-encrypted'

LOG_TO_EMAIL='true'
EMAIL_SENDER='Computer <your.email@address.com>'
# You can use aliases if your mailing system is set up correctly.
EMAIL_RECIPIENT='all'

LOG_TO_FILE='true'
LOG_FILE='/var/log/rsync.log'

#!/bin/bash
#
# backup_enc.sh
#
# Copyright (C)  2019  Franco Masotti <franco.masotti@live.com>.
# Permission is granted to copy, distribute and/or modify this document
# under the terms of the GNU Free Documentation License, Version 1.3
# or any later version published by the Free Software Foundation;
# with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
# A copy of the license is included in the section entitled "GNU
# Free Documentation License".

#
# This backup is intended to be run manually.
#

declare -A BACKUP_ALIAS_ROOT
declare -A BACKUP_ALIAS_DATA

# Get correct path before loading the configuration file.
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
. ""${DIR}"/backup_enc.conf"

WHAT="${1}"

{ command -V cryptsetup && command -V bash && command -V printf \
    && command -V mount && command -V umount && command -V awk; } \
    || exit 1
[ ${UID} -ne 0 ] && printf "%s\n" 'user must be root' 2>&1 && exit 1

if [ "${WHAT}" = 'root' ]; then
    SRC="${BACKUP_ALIAS_ROOT['SRC']}"
    DST="${BACKUP_ALIAS_ROOT['DST']}"
    UUID="${BACKUP_ALIAS_ROOT['UUID']}"
    NAME="${BACKUP_ALIAS_ROOT['DEVICE_MAPPER_NAME']}"
elif [ "${WHAT}" = 'data' ]; then
    SRC="${BACKUP_ALIAS_DATA['SRC']}"
    DST="${BACKUP_ALIAS_DATA['DST']}"
    UUID="${BACKUP_ALIAS_DATA['UUID']}"
    NAME="${BACKUP_ALIAS_DATA['DEVICE_MAPPER_NAME']}"
else
    printf "%s\n" 'error: configuration not set' 2>&1 && exit 1
fi

# Find partition via UUID.
dev="/dev/"$(lsblk -x name -i -o name,uuid | grep "${UUID}" | awk '{print $1}')""
[ -z "${dev}" ] && exit 1

cryptsetup open "${dev}" "${NAME}" && mount /dev/mapper/"${NAME}" "${DST}" \
&& ""${DIR}"/backup.sh" "${SRC}" "${DST}"

umount "${DST}" && cryptsetup close "${NAME}"

#
# backup_enc.conf
#
# Copyright (C)  2019  Franco Masotti <franco.masotti@live.com>.
# Permission is granted to copy, distribute and/or modify this document
# under the terms of the GNU Free Documentation License, Version 1.3
# or any later version published by the Free Software Foundation;
# with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
# A copy of the license is included in the section entitled "GNU
# Free Documentation License".

BACKUP_ALIAS_ROOT['SRC']='/*'
BACKUP_ALIAS_ROOT['DST']='/mnt/backup_root_enc'
BACKUP_ALIAS_ROOT['UUID']='<put the UUID here>'
BACKUP_ALIAS_ROOT['DEVICE_MAPPER_NAME']='root_enc'

BACKUP_ALIAS_DATA['SRC']='/data/*'
BACKUP_ALIAS_DATA['DST']='/mnt/backup_data_enc'
BACKUP_ALIAS_DATA['UUID']='<put the UUID here>'
BACKUP_ALIAS_DATA['DEVICE_MAPPER_NAME']='data_enc'