We're talking several thousand users here. They won't all be writing to the file, but based on certain conditions some will and I would think with that many users there is a possibility that more than one user could be trying to access the file at the same time.

When using RedirectOutput or WriteLine, if user A has the file open for write purposes and user B needs to write at the same time, does user B skip it because it's already open or does he wait?

Why or how can multiple people write to an ini file at the same time but not to a regular file? Does it have to be in any special format?