# the gimp script
(define (img2img in_filename out_filename)
  (let* (
         (image (car (gimp-file-load RUN-NONINTERACTIVE in_filename in_filename)))
	 (layer (gimp-image-flatten image))
         (drawable (car (gimp-image-get-active-layer image)))
         )
    (gimp-file-save RUN-NONINTERACTIVE image drawable out_filename out_filename)
    (gimp-image-delete image)
    )
  )
############################################
# bash script
#!/bin/bash
COMMAND=`basename $0 .sh`
case "$#" in 
    2)
       ;;
    *)
    echo -e "$COMMAND: script for transforming a image with gimp from exts"
    echo -e "usage:\n\t$COMMAND in_filename out_filename\n"
    exit 1
esac
gimp --as-new -dfs -i -b "'(img2img \"$1\" \"$2\")'" -b "'(gimp-quit 0)'"
############################################
# the gimp script called directly from a shell
$ gimp --as-new -dfs -i -b '(img2img "ATSP-A0min.png" "prueba.eps")' -b '(gimp-quit 1)'
batch command executed successfully
$
# the script terminate and generate the file prueba.eps as expected
############################################
# the gimp script called through the bash script
$ img2img  "ATSP-A0min.png" "prueba.eps" 
batch command executed successfully
batch command executed successfully
^C/usr/lib/gimp/2.0/plug-ins/script-fu terminated: Interrupción
gimp: terminated: Interrupción
[gimp never return]
############################################
# the gimp script called through source
$ source  ~/src/bin/img2img.sh  ATSP-A0min.png prueba.eps
batch command executed successfully
batch command executed successfully
^C/usr/lib/gimp/2.0/plug-ins/script-fu terminated: Interrupción
gimp: terminated: Interrupción
[gimp never return]