GNU Emacs Manual - Examining

Examining and Setting Variables

C-h v var RET

Display the value and documentation of variable var (describe-variable ).

M-x set-variable RET var RET value RET

Change the value of variable var to value.

To examine the value of a single variable, use C-h v (describe-variable ), which reads a variable name using the minibuffer, with completion. It displays both the value and the documentation of the variable. For example,

	C-h v fill-column RET

displays something like this:

	fill-column's value is 75
	
	Documentation:
	*Column beyond which automatic line-wrapping should happen.
	Automatically becomes buffer-local when set in any fashion.

The star at the beginning of the documentation indicates that this variable is an option. C-h v is not restricted to options; it allows any variable name.

The most convenient way to set a specific option is with M-x set-variable. This reads the variable name with the minibuffer (with completion), and then reads a Lisp expression for the new value using the minibuffer a second time. For example,

	M-x set-variable RET fill-column RET 75 RET

sets fill-column to 75.

You can set any variable with a Lisp expression using the function setq . Here's how to use it to set fill-column :

	(setq fill-column 75)

Setting variables, like all means of customizing Emacs except where otherwise stated, affects only the current Emacs session.