Update sys.platform doc for #12326.
Backport from Python 3.2 (e11b4c945f7e).
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 6df371f..4afef5a 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -709,28 +709,38 @@
This string contains a platform identifier that can be used to append
platform-specific components to :data:`sys.path`, for instance.
- For Unix systems, this is the lowercased OS name as returned by ``uname -s``
- with the first part of the version as returned by ``uname -r`` appended,
- e.g. ``'sunos5'`` or ``'linux2'``, *at the time when Python was built*.
- Unless you want to test for a specific system version, it is therefore
- recommended to use the following idiom::
+ For most Unix systems, this is the lowercased OS name as returned by ``uname
+ -s`` with the first part of the version as returned by ``uname -r`` appended,
+ e.g. ``'sunos5'``, *at the time when Python was built*. Unless you want to
+ test for a specific system version, it is therefore recommended to use the
+ following idiom::
- if sys.platform.startswith('linux'):
+ if sys.platform.startswith('freebsd'):
+ # FreeBSD-specific code here...
+ elif sys.platform.startswith('linux'):
# Linux-specific code here...
+ .. versionchanged:: 2.7.3
+ Since lots of code check for ``sys.platform == 'linux2'``, and there is
+ no essential change between Linux 2.x and 3.x, ``sys.platform`` is always
+ set to ``'linux2'``, even on Linux 3.x. In Python 3.3 and later, the
+ value will always be set to ``'linux'``, so it is recommended to always
+ use the ``startswith`` idiom presented above.
+
For other systems, the values are:
- ================ ===========================
- System :data:`platform` value
- ================ ===========================
- Windows ``'win32'``
- Windows/Cygwin ``'cygwin'``
- Mac OS X ``'darwin'``
- OS/2 ``'os2'``
- OS/2 EMX ``'os2emx'``
- RiscOS ``'riscos'``
- AtheOS ``'atheos'``
- ================ ===========================
+ ===================== ===========================
+ System :data:`platform` value
+ ===================== ===========================
+ Linux (2.x *and* 3.x) ``'linux2'``
+ Windows ``'win32'``
+ Windows/Cygwin ``'cygwin'``
+ Mac OS X ``'darwin'``
+ OS/2 ``'os2'``
+ OS/2 EMX ``'os2emx'``
+ RiscOS ``'riscos'``
+ AtheOS ``'atheos'``
+ ===================== ===========================
.. seealso::
:attr:`os.name` has a coarser granularity. :func:`os.uname` gives