Config files now can use environment variables. #97.

1 files changed, 5 insertions, 0 deletions

diff --git a/doc/config.rst b/doc/config.rst
index 159a42f5..f6d8f1fc 100644
--- a/doc/config.rst
+++ b/doc/config.rst
@@ -39,6 +39,11 @@ values on multiple lines.
 Boolean values can be specified as ``on``, ``off``, ``true``, ``false``, ``1``,
 or ``0`` and are case-insensitive.
 
+Environment variables can be substituted in by using dollar signs: ``$WORD``
+``${WORD}`` will be replaced with the value of ``WORD`` in the environment.
+A dollar sign can be inserted with ``$$``.  Missing environment variables
+will result in empty strings with no error.
+
 Many sections and values correspond roughly to commands and options in
 the :ref:`command-line interface <cmd>`.