(lispref.info)Global Variables

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Global Variables

   The simplest way to use a variable is "globally".  This means that
the variable has just one value at a time, and this value is in effect
(at least for the moment) throughout the Lisp system.  The value remains
in effect until you specify a new one.  When a new value replaces the
old one, no trace of the old value remains in the variable.

   You specify a value for a symbol with `setq'.  For example,

     (setq x '(a b))

gives the variable `x' the value `(a b)'.  Note that the first argument
of `setq', the name of the variable, is not evaluated, but the second
argument, the desired value, is evaluated normally.

   Once the variable has a value, you can refer to it by using the
symbol by itself as an expression.  Thus,

          => (a b)

assuming the `setq' form shown above has already been executed.

   If you do another `setq', the new value replaces the old one:

          => (a b)
     (setq x 4)
          => 4
          => 4

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