Process on one host cannot see in time file just created by another process on

No. You need to FLUSH the writes and file creations to the disk...otherwise the actual files (or modifications thereto) are still held in buffers and do not exist on the disk as such.

This doesn't matter if ONE application is accessing the files, like a database server that is accessed by multiple clients, which is a better way to do what you want by the way, but if you ant your code to work you need to basically open read-write. flush and close the file as an 'atomic' operation every time it is accessed. If more than one program is doing a write, you need to implement file locking as well.

So the 'real' solid way to go is

while (open says locked)* wait for another process to complete *Lock* you have the file *Read* get the bit needing to be used or modified *Process* modify it *Write* back to the disk buffer caches *Flush* make sure the actual disk reflects the caches *Unlock* so someone else can use it *Close* and free up file pointers etc*

Note that some file sharing systems are NOT good at locking Note that the above drives a horse and cart through smart disk caching algorithms, which is why large multi-user applications that require a lot of shared data access always use a daemon handling file accesses and never allow the user applications access to the actual disk data itself.