Want to monitor process..

[Haeyoung Kim]

I want to run or kill a process(program?) using python.
Once it's started, I don't want to run the same process any more. (but
can be killed or restarted, of course)
At present I use a naive way to write a pid file when initiate the
process, but in that case I can't restart it when the process has been
down. (i.e., if that when the process has gone, I should kill the
processes and remove pid file manually.)
I'm not so good at such a system programming.. :(
Is there any nice solution?
Thank you in advance.