setup.py install builds and installs all modules in one
run. If you prefer to work incrementally--especially useful if you
want to customize the build process, or if things are going wrong--you
can use the setup script to do one thing at a time. This is
particularly helpful when the build and install will be done by
different users--e.g., you might want to build a module distribution
and hand it off to a system administrator for installation (or do it
yourself, with super-user privileges).
For example, you can build everything in one step, and then install everything in a second step, by invoking the setup script twice:
python setup.py build python setup.py install
installcommand first runs the
buildcommand, which--in this case--quickly notices that it has nothing to do, since everything in the build directory is up-to-date.)
You may not need this ability to break things down often if all you do is install modules downloaded off the 'net, but it's very handy for more advanced tasks. If you get into distributing your own Python modules and extensions, you'll run lots of individual Distutils commands on their own.