here is one way
(defun c:dimTextfit ( / ss1)
(princ "\nSelect Dimensions to fit text: ")
(setq ss1 (ssget ":L" '((0 . "*dim*"))))
(if ss1
(progn
;; set dimension variable override
(command "dim1" "dimtmove" "2")
;; update dimensions to override
(command "dim1" "update" ss1 "")
;; reset dimension variable
(command "dim1" "dimtmove" "0")
) ;_progn
(princ "\nNo dimensions selected")
) ;_if
(princ)
)