#!/bin/sh

split_directories() {
  dir="$1"
  while test "$dir" != "/" -a "$dir" != "."; do
    printf "%s\n" "$dir"
    dir=$(dirname "$dir")
  done
}

if test -z "$1"; then
  split_directories "$(pwd)"
else
  for dir in "$@"; do
    case "$dir" in
      /*)  # Absolute path
        split_directories "$dir"
        ;;
      *)  # Relative path
        split_directories "$(pwd)/$dir"
        ;;
    esac
  done
fi