Steven D'Aprano wrote: > I want to rename a file, but only if the destination file name > doesn't already exist. > > I can do this: > > if os.path.exists(dest): > # skip file, raise an exception, make a backup... > do_something_else() > else: > os.rename(src, dest) > > > But on a multi-user system, it is possible that dest is created > in the time period between checking if it exists and attempting > the rename. > > Is there any way to prevent this? Or do I just try to keep the > check and the rename as close together as possible, minimizing > the chances and hoping for the best?
1: Open the file with os.open 2: Lock the file exclusively -> no other process can now access it. 3: Use rename to rename the file; this causes a file system level implicit unlink of the old file (it dissappears from the file system) but the opening process can still access it. 4: close the file -> the lock is removed and the rename finalized. Wolfgang Draxinger -- E-Mail address works, Jabber: [EMAIL PROTECTED], ICQ: 134682867 GPG key FP: 2FC8 319E C7D7 1ADC 0408 65C6 05F5 A645 1FD3 BD3E -- http://mail.python.org/mailman/listinfo/python-list
