gimp script that does not work within shell script

[MVE]

I attach again forum.txt, because the first version is incomplete...
  forum.txt (Size: 1.65 KB / Downloads: 93)

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Bug fixed!
Using de shell invocation into a makefile, I realized that I had a lot of quotes...
In short:
* from the command line:
$    gimp --as-new -dfs -i -b '(img2img "ATSP-A0min.png" "prueba.eps")' -b '(gimp-quit 1)'
* from a Makefile:
%.eps: %.png
    gimp --as-new -dfs -i -b '(img2img "$<" "$@")' -b '(gimp-quit 0)'

* from a shell script:
    gimp --as-new -dfs -i -b '(img2img "'$1'" "'$2'")' -b '(gimp-quit 0)'

So this issue has to do with bash, not with gimp...

That's all, folks!