Not even all UNIXes.

It is implementation defined on the UNIX OS variant and mounted file system.

The beauty of POSIX is how it appears to be portable, while leaving quite a few things being implementation defined.

Not sure what UNIX variant are you thinking, but from POSIX:

> The mmap() function adds an extra reference to the file associated with the file descriptor fildes which is not removed by a subsequent close() on that file descriptor. This reference is removed when there are no more mappings to the file.

I'm sure there have been unix variants that got it wrong and might not even have been in posix from the beginning (it is there since at least SUSv2); still I think this is traditional unix behavior.

Today I learned!

Your comment contains no details whatsoever, then you described perfectly sane mmap behavior, so what do I know?

Windows dosent have the concept of an inode, so there is nothing for a file handle (what windows calls a file descriptor) to bind to except a file name, this means that a filename cannot be removed while it is being accessed somehow.

This is the cause of a lot of woes on windows, such as random access denied errors when attempting to delete stuff, and what forces a reboot when you update nearly anything on windows.

One of my favourite things related to this is that the Windows XP explorer had a bug where clicking on a file would generate a dynamic preview of an audio/video file in the sidebar, which would lock the file, rendering it impossible to delete because you had to click on it first....