Lisp to Run a command Automatically when opened the file

(defun PurgeMe ()
 (if (= (length (vl-remove-if '(lambda(x)(or (< x 48)(> x 57)))
                  (vl-string->list (vl-filename-base (getvar 'DWGNAME))))) 7)
   (progn
     ; purge everything
     (vla-purgeall (vla-get-activedocument (vlax-get-acad-object)))
     ; maybe do a zoom extents
     (vla-ZoomExtents (vlax-get-acad-object))
     ; save drawing
     (command ".qsave")
   )
 )
 (princ)
)

;; Auto-run on start up of drawing names that their names are consist of digits only.
(PurgeMe)

Excellent Rlx. You saved me.

Thank you so much for your code.. this is working as what i want.

Thank you so much all of you for your effort on this.