starting and stopping a program from inside a python script

[dfaber]

Aloha!
 I want to terminate a process/program from within a python script.

For example,
if I have a program say foo.sh that starts running, then I can run it
from within a python script using
os.popen('foo.sh') which starts a program/process say 'bar'

At some point later,  I want to kill 'bar'. Currently, I start off the
process and then when the python script exits, the process 'bar' is
still running and I have to issue ps -ef  | grep 'bar' and then kill
it.

Is there any better way of doing this?