5 Extension modules

Eshell provides a facility for defining extension modules so that they can be disabled and enabled without having to unload and reload them, and to provide a common parent Customize group for the modules.⁹ An Eshell module is defined the same as any other library but one requirement: the module must define a Customize¹⁰ group using eshell-defgroup (in place of defgroup) with eshell-module as the parent group.¹¹ You also need to load the following as shown:

(eval-when-compile
  (require 'cl-lib)
  (require 'esh-mode)
  (require 'eshell))

(require 'esh-util)