#!/bin/zsh

call=$0
real=$call

die() {
  echo "$*" >/dev/stderr
  exit 1
}

while [ -L "$real" ]; do
  real="$(stat -c %N "$real" |sed -r "s:..*. -> .(.*).$:\1:")"
done

_EXEC="$(dirname "$real")"  #execution directory
_STOR="$(dirname "$call")"  #storage directory

[ -w "$_EXEC" ] && [ -d "$_EXEC" ] || die "storage directory must be writable"

echo ex: $_EXEC
echo st: $_STOR