check if file exist on ntfs partition to decide default boot order

[Jarek]

Hi!

I want to check if specific file (let's say win.txt) exist in root 
directory at ntfs WIndows partition and if does, then boot Windows (or 
better: make it default choice but still display menu and timeout), and 
if not boot Linux (or leave default menu with default Linux and 
timeout). I've seen command test -e file and insmod ntfs, but I don't 
know what next. Does "grub works" like shell scripts? Are entries from 
grub.cfg are just interpreted and executed from top to bottom or is it 
compiled on update?

Jarek