Added cross-references to venv definition.

Doc/library/sys.rst

@@ -32,10 +32,11 @@ always available.
 .. data:: base_exec_prefix
 
    Set during Python startup, before ``site.py`` is run, to the same value as
-   :data:`exec_prefix`. If not running in a virtual environment, the values
+   :data:`exec_prefix`. If not running in a
-   will stay the same; if ``site.py`` finds that a virtual environment is in
+   :ref:`virtual environment <venv-def>`, the values will stay the same; if
-   use, the values of :data:`prefix` and :data:`exec_prefix` will be changed to
+   ``site.py`` finds that a virtual environment is in use, the values of
-   point to the virtual environment, whereas :data:`base_prefix` and
+   :data:`prefix` and :data:`exec_prefix` will be changed to point to the
+   virtual environment, whereas :data:`base_prefix` and
    :data:`base_exec_prefix` will remain pointing to the base Python
    installation (the one which the virtual environment was created from).
 
@@ -45,7 +46,7 @@ always available.
 .. data:: base_prefix
 
    Set during Python startup, before ``site.py`` is run, to the same value as
-   :data:`prefix`. If not running in a virtual environment, the values
+   :data:`prefix`. If not running in a :ref:`virtual environment <venv-def>`, the values
    will stay the same; if ``site.py`` finds that a virtual environment is in
    use, the values of :data:`prefix` and :data:`exec_prefix` will be changed to
    point to the virtual environment, whereas :data:`base_prefix` and
@@ -241,9 +242,10 @@ always available.
    installed in :file:`{exec_prefix}/lib/python{X.Y}/lib-dynload`, where *X.Y*
    is the version number of Python, for example ``3.2``.
 
-   .. note:: If a virtual environment is in effect, this value will be changed
+   .. note:: If a :ref:`virtual environment <venv-def>` is in effect, this
-      in ``site.py`` to point to the virtual environment. The value for the
+      value will be changed in ``site.py`` to point to the virtual environment.
-      Python installation will still be available, via :data:`base_exec_prefix`.
+      The value for the Python installation will still be available, via
+      :data:`base_exec_prefix`.
 
 
 .. data:: executable
@@ -865,9 +867,10 @@ always available.
    stored in :file:`{prefix}/include/python{X.Y}`, where *X.Y* is the version
    number of Python, for example ``3.2``.
 
-   .. note:: If a virtual environment is in effect, this value will be changed
+   .. note:: If a :ref:`virtual environment <venv-def>` is in effect, this
-      in ``site.py`` to point to the virtual environment. The value for the
+      value will be changed in ``site.py`` to point to the virtual
-      Python installation will still be available, via :data:`base_prefix`.
+      environment. The value for the Python installation will still be
+      available, via :data:`base_prefix`.
 
 
 .. data:: ps1

Doc/library/venv.rst

@@ -88,7 +88,7 @@ a Posix platform, you would typically do::
 
 whereas on Windows, you might do::
 
-    c:\> <venv>/Scripts/activate
+    C:\> <venv>/Scripts/activate
 
 if you are using the ``cmd.exe`` shell, or perhaps::
 
@@ -108,6 +108,8 @@ a "deactivate" function, whereas on Windows there are separate scripts called
 ``deactivate.bat`` and ``Deactivate.ps1`` which are installed when the venv is
 created.
 
+.. _venv-def:
+
 .. note:: A virtual environment (also called a ``venv``) is a Python
    environment such that the Python interpreter, libraries and scripts
    installed into it are isolated from those installed in other virtual

Doc/using/scripts.rst

@@ -6,8 +6,8 @@ Additional Tools and Scripts
 pyvenv - Creating virtual environments
 --------------------------------------
 
-Creation of virtual environments is done by executing the ``pyvenv``
+Creation of :ref:`virtual environments <venv-def>` is done by executing the
-script::
+``pyvenv`` script::
 
     pyvenv /path/to/new/virtual/environment
 
@@ -72,7 +72,7 @@ a Posix platform, you would typically do::
 
 whereas on Windows, you might do::
 
-    c:\> <venv>/Scripts/activate
+    C:\> <venv>/Scripts/activate
 
 if you are using the ``cmd.exe`` shell, or perhaps::
 
@@ -92,25 +92,3 @@ a "deactivate" function, whereas on Windows there are separate scripts called
 ``deactivate.bat`` and ``Deactivate.ps1`` which are installed when the venv is
 created.
 
-.. note:: A virtual environment (also called a ``venv``) is a Python
-   environment such that the Python interpreter, libraries and scripts
-   installed into it are isolated from those installed in other virtual
-   environments, and (by default) any libraries installed in a "system" Python,
-   i.e. one which is installed as part of your operating system.
-
-   A venv is a directory tree which contains Python executable files and
-   other files which indicate that it is a venv.
-
-   Common installation tools such as ``distribute`` and ``pip`` work as
-   expected with venvs - i.e. when a venv is active, they install Python
-   packages into the venv without needing to be told to do so explicitly.
-
-   When a venv is active (i.e. the venv's Python interpreter is running), the
-   attributes :attr:`sys.prefix` and :attr:`sys.exec_prefix` point to the base
-   directory of the venv, whereas :attr:`sys.base_prefix` and
-   :attr:`sys.base_exec_prefix` point to the non-venv Python installation
-   which was used to create the venv. If a venv is not active, then
-   :attr:`sys.prefix` is the same as :attr:`sys.base_prefix` and
-   :attr:`sys.exec_prefix` is the same as :attr:`sys.base_exec_prefix` (they
-   all point to a non-venv Python installation).
-