Command line actions

Hi,
I’m searching for a way to automate the production of output files

My purpose is to create some sort of “build script” that would generate various files in a similar way that make would to for C/C++ files.
In fact I was planning to use make with recipies like

$(BUILDDIR)/$(PROJECTNAME).pdf $(PROJECTNAME).pro
@kicad $< --plot-all -o $@

are there undocumented command line options that would do the job ?

Unfortunately no. See https://gitlab.com/kicad/code/kicad/issues/2475.