From 1fcb1b5bc195922602ef77a6e3fba2cb5c1c08c7 Mon Sep 17 00:00:00 2001
From: Tim Hughes <thughes@thegoldfish.org>
Date: Wed, 15 Jan 2020 10:40:01 +0000
Subject: [PATCH] [docs] mention variable expansion in `.env` files

fix #3610
---
 docs/advanced.rst | 17 +++++++++++++++++
 news/4100.doc.rst |  1 +
 2 files changed, 18 insertions(+)
 create mode 100644 news/4100.doc.rst

diff --git a/docs/advanced.rst b/docs/advanced.rst
index 9efb798eb1..014bd62d27 100644
--- a/docs/advanced.rst
+++ b/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
 -------------------------
 
diff --git a/news/4100.doc.rst b/news/4100.doc.rst
new file mode 100644
index 0000000000..050bdcca96
--- /dev/null
+++ b/news/4100.doc.rst
@@ -0,0 +1 @@
+More documentation for ``.env`` files