Programming

I am programming some data loader of oracle with unix c, when I find new data file, then read it to database and delete it. but one issue, if the file is in process of creating, not been closed yet. I will read zero or part of data content, this will cause problem. I want to know whether some unix system function can check this situation, avoid it.

Thanks!

You really need some cooperation from the creating process to achieve the best solution. The creating process should open a temporary filename and write to that. Once it is done, it should rename the file to the real name. That way, when your program sees the real filename appear, it will know that it can proceed.

Perderabo is correct some handshaking will be required.

Some OS may provide low level file locking facilities but these may not be guaranteed or portable.

Another way of indicating a file has been completed is an associated 'trigger file'. e.g. myfile and myfile.trig

The 'trigger' file will be an empty file and simply indicate the the real file is ready for processing.

The naming convention is aribrary but the method could be used if there are restrictions in unique file naming from the system for whatever reason.

Either method would be OK, it is just a matter of how you decide to implement your handshaking between processes.

MBB