Session files: Expand environment variables

docs/changelog.rst

@@ -57,6 +57,8 @@ Detailed list of changes
 
 - Allow using the cwd of the original process for :option:`launch --cwd` (:iss:`5672`)
 
+- Session files: Expand environment variables (:disc:`5917`)
+
 - Pass key events mapped to scroll actions to the program running in the terminal when the terminal is in alternate screen mode (:iss:`5839`)
 
 - Implement :ref:`edit-in-kitty <edit_file>` using the new ``kitten`` static executable (:iss:`5546`, :iss:`5630`)

docs/overview.rst

@@ -173,6 +173,11 @@ option in :file:`kitty.conf`. An example, showing all available commands:
     The :doc:`launch <launch>` command when used in a session file cannot create
     new OS windows, or tabs.
 
+.. note::
+   Environment variables of the for :code:`${NAME}` or :code:`$NAME` are
+   expanded in the session file, except in the *arguments* (not options) to the
+   launch command.
+
 
 Creating tabs/windows
 -------------------------------