dfree for samba that treats ZFS as a special case

dfree

#!/usr/bin/env bash
# vim: set et ts=2 sw=2:
# changes: run through shellcheck, fixing several bugs

set -euo pipefail

HERE="$(realpath "$1")"

if findmnt --noheadings --output FSTYPE --target "$HERE" | grep -Pq '^zfs$'; then
  echo "dfree: $HERE is zfs" >&2
  USED_BYTES=$(zfs get -o value -Hp used "$HERE")
  AVAIL_BYTES=$(zfs get -o value -Hp available "$HERE")
  USED=$((USED_BYTES/1024))
  AVAIL=$((AVAIL_BYTES/1024))
  TOTAL=$((USED+AVAIL))
  echo "$TOTAL $AVAIL"
else
  echo "dfree: $HERE is NOT zfs" >&2
  df -k --output=size,avail "$HERE" | tail -1
fi