Variable: initial-major-mode
initial-major-mode is a customizable variable defined in
startup.el.gz.
Value
lisp-interaction-mode
Documentation
Major mode command symbol to use for the initial *scratch* buffer.
Probably introduced at or before Emacs version 21.2.
Source Code
;; Defined in /usr/src/emacs/lisp/startup.el.gz
(defcustom initial-major-mode 'lisp-interaction-mode
"Major mode command symbol to use for the initial `*scratch*' buffer."
:type 'function)