Merge pull request #4100 from timhughes/dotenv_docs

Dotenv docs

docs/advanced.rst

@@ -344,6 +344,21 @@ If a ``.env`` file is present in your project, ``$ pipenv shell`` and ``$ pipenv
     >>> os.environ['HELLO']
     'WORLD'
 
+Shell like variable expansion is available in ``.env`` files using `${VARNAME}` syntax.::
+
+    $ cat .env
+    CONFIG_PATH=${HOME}/.config/foo
+
+    $ pipenv run python
+    Loading .env environment variables…
+    Python 3.7.6 (default, Dec 19 2019, 22:52:49)
+    [GCC 9.2.1 20190827 (Red Hat 9.2.1-1)] on linux
+    Type "help", "copyright", "credits" or "license" for more information.
+    >>> import os
+    >>> os.environ['CONFIG_PATH']
+    '/home/kennethreitz/.config/foo'
+
+
 This is very useful for keeping production credentials out of your codebase.
 We do not recommend committing ``.env`` files into source control!
 
@@ -355,6 +370,8 @@ To prevent pipenv from loading the ``.env`` file, set the ``PIPENV_DONT_LOAD_ENV
 
     $ PIPENV_DONT_LOAD_ENV=1 pipenv shell
 
+See `theskumar/python-dotenv <https://github.com/theskumar/python-dotenv>`_ for more information on ``.env`` files.
+
 ☤ Custom Script Shortcuts
 -------------------------
 

news/4100.doc.rst

@@ -0,0 +1 @@
+More documentation for ``.env`` files