My backup script for synology NAS, with safety checks for archival

backup-nas.sh

#!/bin/bash
set -eu

found_not_mounted=0
function check_not_empty() {
  local path="$1"
  if [ ! -d "$path" ]; then
    found_not_mounted=1
    echo "ERROR: $path does not exist!"
  elif [ ! "$(ls -A "$path")" ]; then
    found_not_mounted=1
    echo "ERROR: $path is empty!"
  fi
}

# Check all fancy encrypted volumes to backup are properly mounted!
check_not_empty /nas
check_not_empty /nas/Archive
check_not_empty /nas/Dibujos
check_not_empty /nas/FileHistory

if [ "$found_not_mounted" -ne 0 ]; then
  echo "Please make sure /nas is mounted and all encrypted volumes in the NAS Shared Folders are also properly mounted."
  exit 1
fi

DRIVE_GLOB="/run/media/ntrrgc/NAS-*"

DRIVE=""
for drive in $(ls -1 -d $DRIVE_GLOB); do
  if [ -z "$DRIVE" ]; then
    DRIVE="$drive"
  else
    echo "Ambiguous drive selection, there are more than one possible NAS backup drives!"
    ls -1 -d $DRIVE_GLOB
    exit 1
  fi
done
if [ -z "$DRIVE" ]; then
  echo "Plug and mount a NAS backup drive in $DRIVE_GLOB!"
  exit 1
fi

echo "Backing up NAS in $DRIVE..."
sleep 3s # to confirm... enough time to ^C if it goes haywire

export RSYNC_PASSWORD=YOUR_SYNOLOGY_RYSNC_PASS
RSYNC_EXCLUDE_OPTS=(--exclude '*@SynoEAStream' --exclude '*@SynoResource' --exclude '@eaDir' --exclude '#recycle')
RSYNC_SRC="rsync://ntrrgc@mami.local"
DRY_RUN_EXCLUDE=(grep -vi 'Thumbs.db')

found_deletions=0
deletions_msg=""

function archive_check() {
  local nas_path="$1" # must NOT start or end with /
  mkdir -p /tmp/backup-nas-dry-run/"$nas_path"
  local dry_run_file="/tmp/backup-nas-dry-run/$nas_path/dry-run.txt"

  echo "Checking for deletions in $nas_path..."
  rsync -aXx "${RSYNC_EXCLUDE_OPTS[@]}" --delete --inplace -nv "$RSYNC_SRC/$nas_path/" "$DRIVE/$nas_path" > "$dry_run_file" 2>&1
  if cat "$dry_run_file" | "${DRY_RUN_EXCLUDE[@]}" | grep '^deleting '; then
    found_deletions=1
    local count=$(cat "$dry_run_file" | "${DRY_RUN_EXCLUDE[@]}" | grep -c '^deleting ')
    deletions_msg="${deletions_msg}$count deletions have been found in $nas_path."$'\n'
  fi
}

function request_delete_confirmation() {
  if [[ "$found_deletions" -ne 0 ]]; then
    deletions_msg="${deletions_msg}Please check everything is right and confirm to continue the backup with the deletions."
    telegram-notify send "$deletions_msg"
    echo "You can check the full dry-run logs in /tmp/backup-nas-dry-run. Type 'yes' to continue with the backup deleting the files above from the backup drive."
    echo -n "Continue? "
    read answer
    if [[ "$answer" != "yes" ]]; then
      echo "Cancelling backup."
      exit 1
    fi
  fi
}

function sync_folder() {
  local nas_path="$1" # must NOT start or end with /

  # --inplace should make synchronization of big files (e.g. disk images) faster
  rsync -aXx --info=progress2 \
    "${RSYNC_EXCLUDE_OPTS[@]}" \
    --delete --inplace \
    "$RSYNC_SRC/$nas_path/" "$DRIVE/$nas_path/"
}

# Deleting files from the backup in these directories will need confirmation (they are intended to be mostly addition-only).
archive_check Archive
archive_check Dibujos
archive_check photo

request_delete_confirmation

sync_folder Archive
sync_folder Dibujos
sync_folder photo
sync_folder homes
sync_folder FileHistory

date | sudo tee "$DRIVE/last-backup-date.txt" > /dev/null
if safely-remove "$DRIVE"; then
  telegram-notify send "Finished backing up NAS into $DRIVE. You can now unplug the drive."
else
  telegram-notify send "Finished backing up NAS into $DRIVE. COULDN'T UNMOUNT THE DEVICE, IT MAY STILL BE IN USE."
fi