how to generate a signal when a Data is written into file?

Question

When ever C program exectues it produces error or executes sucessfully. If it produces error I am redirecting the error to a file error.log. I want a Signal (notification) to be generated as soon as a write action takes place on error.log, this signal should invoke another program say, Parser.c which will read the error.log copy into buffer and clear the contents of log file.

Is it possible that a file generates a signal to invoke another program if yes then how can we achieve it programmatically?

Answer 1

I believe the answer will be different on different systems. I would suggest that you just start that other program from the first program (fork a new process on Linux) after you are done writing on file.

Answer 2

One way would be to use the asynchronous I/O mechanism (aio_*), these will send a signal as specified in the AIO control block (check the man page for further details, it's pretty complete). Essentially you would be setting up an AIO control block for reading, and issue an aio_read(). When the signal is received, you would process the data. aio(7) for Linux is a pretty useful man page regarding this.