Child Processes of Child Processes

[ldb88]

My python script launches program A. Program A launches program B. Program A closes without waiting for program B to complete. How can I know when program B completes?

This is on a Windows XP machine. Thanks!

[kaarthikeyapreyan]

My python script launches program A. Program A launches program B. Program A closes without waiting for program B to complete. How can I know when program B completes?

This is on a Windows XP machine. Thanks!

The script that launches the program A is the parent of program and A launches another program B which is the grandchild of the main script. I believe that since that A launches B the process for A is still on the run,if A terminates then B must also terminate unless its launched as a orphan process or a daemon process. B returns a exit status to its parent A stating that its job is done. we can catch the exit status of the program once its completed or to know that its successfully completed.

[ldb88]

Thanks for replying.

I'm not sure how program A launches program B, but I managed to find a way to get the pid of process B.

The only problem is that os.waitpid(pid, 0) doesn't work. It says no child process, but in the documentation I see that any pid should work, whether it is a child or not.

Is there something special I have to do with the pid for it to work? The pid I am using is the one that the Task Manager shows.

Thanks.

[micmast]

I don't know how the code looks, but you might want to consider using popen, that contains a pid for the child processes. Also the program can wait for the program to finish before continuing it's execution (termination).

[ldb88]

I'm been running this from Cygwin, but giving it the Windows pid. Is there a way to specify that I want to wait for a Windows pid without having to exit Cygwin, reopen, and then continuing?

EDIT: Actually, that won't work either. I can't wait for a pid whether I go through cygwin or cmd.exe.