In article <[EMAIL PROTECTED]>, Donn Cave <[EMAIL PROTECTED]> writes: |> > |> |> > |> O_EXCL fails if the file exists at all - whether closed or open. |> > |> > Yes. In theory. In practice, it usually works on normal files, provided |> > that all opens are local. Under some circumstances, it will even work |> > for NFS mounted files, as far as I recall. |> |> Mm, by "fail", I meant |> |> An attempt to open with O_EXCL set will "fail" if the file exists at all, |> i.e., the file will not be opened, a negative value will be returned, |> and errno will be set to EEXIST. |> |> What I neglected to mention is that this effect obtains when O_EXCL |> is used in combination with O_CREAT. Without O_CREAT, O_EXCL doesn't |> mean anything and is ignored. |> |> If there is any significant difference between theory and practice |> in this matter, it's news to me.
Actually, it is undefined behaviour in POSIX, and I have used a Unix where O_EXCL on its own failed if the file existed (of course, it also failed if it DIDN'T exist, because of the lack of O_CREAT). I can't remember which - perhaps AIX or OSF/1 (not DEC). But I was referring to a different problem. Some remote and parallel filing systems handle such things very badly, and it is often possible to create a file even if it exists and O_CREAT|O_EXCL is set. A similar remark applies to 'special' files, even on fairly mainstream, local filing systems. Regards, Nick Maclaren. -- http://mail.python.org/mailman/listinfo/python-list
