How to wait for exit of non-children processes

Question

For child processes, the wait() and waitpid() functions can be used to suspends execution of the current process until a child has exited. But t

Answer 1

You could also create a socket or a FIFO and read on them. The FIFO is especially simple: Connect the standard output of your child with the FIFO and read. The read will block until the child exits (for any reason) or until it emits some data. So you'll need a little loop to discard the unwanted text data.

If you have access to the source of the child, open the FIFO for writing when it starts and then simply forget about it. The OS will clean the open file descriptor when the child terminates and your waiting "parent" process will wake up.

Now this might be a process which you didn't start or own. In that case, you can replace the binary executable with a script that starts the real binary but also adds monitoring as explained above.