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 70
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 a user option. C-h v is not restricted to user
options; it allows any variable name.
The most convenient way to set a specific user 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.
M-x set-variable is limited to user option variables, but you can
set any variable with a Lisp expression, using the function setq.
Here is a setq expression to set fill-column:
(setq fill-column 75)
To execute an expression like this one, go to the *scratch*
buffer, type in the expression, and then type C-j. See Lisp Interaction.
Setting variables, like all means of customizing Emacs except where
otherwise stated, affects only the current Emacs session.
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