Document the /dev/null special case.

diff --git a/futatabi.rst b/futatabi.rst
index 75d947a87fa5d4b35837904b5ac8ec1788c9d4f4..171f861f25c59853dde675b30106d21fbe7f7a88 100644 (file)
--- a/futatabi.rst
+++ b/futatabi.rst
@@ -74,7 +74,9 @@ directory (you can change it with the -d option). This holds all of the
 recorded frames, all metadata about clips, and preferences set from the menus
 (interpolation quality and cue point padding).  If you quit Futatabi and
 restart it (or you go down as the result of a power failure or the likes),
-it will remember all the state and frames for you.
+it will remember all the state and frames for you. As a special case,
+if you give */dev/null* in place of an input URL or file, you can keep using
+your workspace without getting any new frames added.
 
 .. _basicui: