ext-backup

#!/usr/bin/env bash
# back up /{etc,home,var} to a LUKS encrypted external drive

# TODO: add options for progress bar, no output and verbose (current)
# TODO: make include and exclude patterns as variables
# TODO: allow these to be passed as arguments
includeFile="${HOME}/bin/.rInclude"
excludeFile="${HOME}/bin/.rExclude"

cryptDevice="external"
externalDrive="/dev/sdc"
mountPoint="/mnt"

logLocation="/tmp/ext-backup_$(date '+%s').log"
USER_HOME="$(getent passwd "${SUDO_USER}" | cut -d':' -f6)"

check_disk() {
  # TODO: this section is finicky, make sure it responds properly
  if lsblk -l | grep "/dev/mapper/${cryptDevice}" >/dev/null; then
    cryptsetup open "${externalDrive}" "${cryptDevice}"
    printf -- '%s\n' "'${externalDrive}' opened as '${cryptDevice}'"
  else
    printf -- '%s\n' "'${externalDrive}' already open as '${cryptDevice}'"
  fi

  if ! df | awk '{print $6}' | grep "${mountPoint}" >/dev/null; then
    mount "/dev/mapper/${cryptDevice}" "${mountPoint}"
    printf -- '%s\n' "'${cryptDevice}' mounted to ${mountPoint}"
  elif [[ "$(df '/mnt' | awk 'NR==2 {print $1}')" == "/dev/mapper/${cryptDevice}" ]]; then
    printf -- '%s\n' "'${cryptDevice}' already mounted to '${mountPoint}'"
  else
    unmount_close "'${mountPoint}' in use by another device"
    exit 1
  fi

  printf -- '%s\n%s\n' "Disk successfully decrypted and mounted." "Ready for backup."
  return 0
}

check_root() {
  # exit if user is not root
  if (("$(id -u)" != 0)); then
    print_errors "Run as root." "Cancelling operation."
    exit 1
  fi
}

sync_main() {
  # sync user's "/home" and then "/var" and "/etc"
  # if you want to add another dir, just provide it as an arg to sync_dirs
  # TODO: make verbosity an option
  if ! rsync -acmuz \
    --info=progress2 \
    --exclude-from="${excludeFile}" \
    --include-from="${includeFile}" \
    --delay-updates \
    --delete-delay \
    --delete-excluded \
    --ignore-existing \
    --log-file="${logLocation}" \
    "${USER_HOME}" "${mountPoint}"; then
    unmount_close "Syncing '${USER_HOME}' failed"
    exit 4
  else
    printf -- '%s\n' "'/home' successfully synced"
  fi

  if ! sync_dirs "/etc" "/var"; then
    unmount_close "Syncing '/etc' and/or '/var' failed"
    exit 4
  else
    printf -- '%s\n' "'/etc' and '/var' successfully synced"
  fi
  return 0
}

sync_dirs() {
  # run through all given directories to copy them, ignoring temp files
  while (("$#")); do
    rsync -mapy \
      --exclude='*.cache' \
      --exclude='*cache/' \
      --exclude='*.tmp' \
      --exclude='*tmp/' \
      --info=progress2 \
      --delay-updates \
      --delete-delay \
      --delete-excluded \
      --ignore-existing \
      --log-file="${logLocation}" \
      "$1" "${mountPoint}"
    shift
  done
  return 0
}

print_errors() {
  tput setaf 1
  printf -- '[ERR] %s\n' "$*" >&2
  tput sgr0
}

unmount_close() {
  # unmount the external drive and close the LUKS container
  if (($# == 1)); then
    print_errors "Error: $1!"
    read -rp "Unmount and close disk? [Y/n] " closeDisk
    case "$closeDisk" in
    y | Y)
      :
      ;;
    *)
      printf -- '%s\n' "Leaving '${externalDrive}' decrypted and mounted."
      exit 2
      ;;
    esac
  fi
  umount "${mountPoint}"
  cryptsetup close "${cryptDevice}"
  return 0
}

main() {
  check_root
  check_disk
  sync_main
  unmount_close
}

main
exit 0