how to create xcf file from given image? (gimp-related)

I've searched for a program on the internet and i couldn't find one. I have to convert my files on my Linux installation with Gimp.

#!/bin/sh
# dmmANY2XCF.sh
# Invoke The GIMP with Script-Fu dmmANYtoXCF.scm
# No error checking.
if [ ! -e $1 ]
then
echo "Usage: dmmANYtoXCF.sh filename"
echo "Error: Parameter (filename) required"
exit 1
fi

gimp -c -i -d -b "(dmmANYtoXCF \"$1\" \"`basename $1`.xcf\")" -b "(gimp-quit 0)"

; dmmANYtoXCF - GIMP Script-Fu to convert an image to XCF firmat
; This Script-Fu must be put in The GIMP's script directory
; (e.g., $HOME/.gimp-1.2/scripts).
; For command-line invocation, use the shell script dmmANYtoXCF.sh
; For interactive invocation, run The GIMP and go to
; Xtns -> Script-Fu -> dmm
;
(define (dmmANYtoXCF infile outfile)
(let* ((image (car (gimp-file-load 1 infile infile)))
(drawable (car (gimp-image-active-drawable image)))
)

(gimp-file-save 1 image drawable outfile outfile )
)
)


(script-fu-register ; I always forget these ...
"dmmANYtoXCF" ; script name to register
"<Toolbox>/Xtns/Script-Fu/dmm/dmmANYtoXCF" ; where it goes
"dmm ANY image (RGB or Indexed) to XCF" ; script description
"Yakov Mindelis (adapted from D. M. MacMillan's PNGtoGRAYSCALE)" ; author
"Copyright 2009 by Yakov Mindelis; GNU GPL" ; copyright
"2009-02-15" ; date
"" ; type of image
SF-FILENAME "Infile" "infile" ; default parameters
SF-FILENAME "Outfile" "outfile"
)