ln -f

[Guy Harris]

>But that doesn't give the same result.  If you remove file2 first, then
>there is a brief window between the 'rm' and the 'ln' during which no
>file named file2 exists.  
>If you use a version of 'ln' that clobbers file2 and replaces it with a
>link to file1 in an atomic operation, there is no such window.

As far as I know, there's no such atomic operation, either; I sure
haven't seen any such operation in any UNIX system I've ever run into.

Given that, every version of "ln" I know of that removes the target
first has to first "unlink()" the target, and then do the "link()".  As
such, the window is still there....