running an app as user "foo"

[bruce]

hi.

within python, what's the best way to automatically spawn an app as a given
user/group.

i'm testing an app, and i'm going to need to assign the app to a given
user/group, as well as assign it certain access rights/modes (rwx) i then
want to copy the test app to a given dir, and then spawn a process to run
the app..

thanks