#!/bin/bash

SRC="/data_to_backup/"  # Replace with the source directory you want to back up
DEST="/backup/"         # Replace with your ZFS pool mount point on the USB drive

# Use rsync with hard links to save space and make incremental backups
rsync -aAXHv --delete --progress \
      --link-dest="$DEST/latest" \
      "$SRC" "$DEST/backup-$(date +%F)"

# Update the "latest" symlink to point to the newest backup
rm -rf "$DEST/latest"
ln -s "$DEST/backup-$(date +%F)" "$DEST/latest"

# Delete backups older than 7 days
find "$DEST" -maxdepth 1 -type d -name "backup-*" -mtime +7 -exec rm -rf {} \;