<p>I'm pretty sure one would do this using the os.plock(op) function, but I have no idea how. Also, if there's a better way, I'd be grateful to find out. Code snippets are very welcome. </p>

This is pretty much Python-independent!  It's a classic example of Unix interprocess communication.  One good option is to use
```
popen()
```
to open a pipe between the parent and child processes, and pass data/messages back and forth along the pipe.
Take a look at the
```
subprocess
```
module
, which can set up the necessary pipes automatically while spawning child processes.