.. note:: On Mac OS X, :func:`getgroups` behavior differs somewhat from

other Unix platforms. If the Python interpreter was built with a

deployment target of :const:`10.5` or earlier, :func:`getgroups` returns

the list of effective group ids associated with the current user process;

this list is limited to a system-defined number of entries, typically 16,

and may be modified by calls to :func:`setgroups` if suitably privileged.

If built with a deployment target greater than :const:`10.5`,

:func:`getgroups` returns the current group access list for the user

associated with the effective user id of the process; the group access

list may change over the lifetime of the process, it is not affected by

calls to :func:`setgroups`, and its length is not limited to 16. The

deployment target value, :const:`MACOSX_DEPLOYMENT_TARGET`, can be

obtained with :func:`sysconfig.get_config_var`.

.. note:: On Mac OS X, the length of *groups* may not exceed the

system-defined maximum number of effective group ids, typically 16.

See the documentation for :func:`getgroups` for cases where it may not

return the same group list set by calling setgroups().