hello list, just added my self so i hope this is an active list.
im am attempting to batch compress OSM tile images. they are of png
format, otherwise i would have used cjpeg.
anyhow the script need only open the images in a folder and save them
out with a different compression level 
after reading the  batch mode page i have assembled this format:
(define (png-compress filename
(let* ((filelist (cadr (file-glob pattern 1))))
(while (not (null? filelist))
(let* ((filename (car filelist))
(image (car (gimp-file-load RUN-NONINTERACTIVE
(gimp-file-png-save RUN-NONINTERACTIVE image drawable
(set! filelist (cdr filelist)))))
$ gimp -i -b '(png-compress "*.png" 9)' -b '(gimp-quit 0)'
but i get:
batch command: experienced an execution error.
got to say i really dont understand scripting all that much, i just
really need to compress these files.
thanks to anyone who can help me out here
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