POSIX v. reality: A position on O_PONIES

I strongly endorse the parent comment. This is how I was taught to write robust Unix software back in the 80s (talk into the good ear, sonny), and the reason had nothing to do with the accidental properties of the ext3 file system, which had not yet been invented. I recall discussing what I thought were oddities of the elm mailer with its author, Dave Taylor, and he explained all the paranoid hoops he jumped through to try to assure that the user would not lose his/her mail despite application crashes, disk-full conditions and the like. The rename pattern was a part of the solution, along with lots of consistency checking.