simplest way to visit 3 subdirectories with a command?

[Tim Chase]

> could you inform how to compose a py-file (for soft installation),
> that will visit 3 subdirectories (eg subdir1, subdir2, subdir3) and
> invoke a command "python setup.py install" in each subdirectory?
> I know there should be a simple solution available in Python

If you're executing "python setup.py install", that sounds like 
you're operating at the shell level, not within python.  In which 
case, I'd just use my shell's iteration capabilities:

   # running bash on a *nix-like OS
   bash$ for dir in subdir1 subdir2 subdir3; do pushd $dir; 
python setup.py install; popd; done

   # running within Win32's cmd.exe
   c:\temp\> for %f in (subdir1 subdir2 subdir3) do pushd %f & 
python setup.py install & popd

or something of the sort.  Remember in Win32 that the variables 
have to be escaped if you put them in a batch file ("%%f" instead 
of "%f")

-tkc