27.2.3 Editing Variable Values

M-x list-options

Display a buffer listing names, values, and documentation of all options.

M-x edit-options

Change option values by editing a list of options.

M-x list-options displays a list of all Emacs option variables in an Emacs buffer named ‘*List Options*’. Each option is shown with its documentation and its current value. Here is what a portion of it might look like:

;; exec-path:
("." "/usr/local/bin" "/usr/ucb" "/bin" "/usr/bin" "/u2/emacs/etc")
*List of directories to search programs to run in subprocesses.
Each element is a string (directory name)
or nil (try the default directory).
;;
;; fill-column:
75
*Column beyond which automatic line-wrapping should happen.
Automatically becomes local when set in any fashion.
;;

M-x edit-options goes one step further and immediately selects the ‘*List Options*’ buffer; this buffer uses the major mode Options mode, which provides commands that allow you to point at an option and change its value:

s

Set the variable point is in or near to a new value read using the minibuffer.

x

Toggle the variable point is in or near: if the value was nil, it becomes t; otherwise it becomes nil.

1

Set the variable point is in or near to t.

0

Set the variable point is in or near to nil.

n

p

Move to the next or previous variable.