One way of processing shell scripts through the C preprocessor + strip comments. Beware that cpp may do surprising things to shell scripts.

Makefile

RELEASE ?= 0

%: %.in
	@$(eval SHEBANG=$(shell head -1 ${<} | grep -q -F '#!' && echo 1 || echo 0))
	@if [ $(SHEBANG) = 1 ]; then \
	  head -1 $< > $@; \
	  tail -n +2 $< | sed -e 's/^ *# .*$$//' -e '/^$$/d' -e '/^#$$/d' | cpp -DRELEASE=$(RELEASE) -P >> $@; \
	else \
	  sed -e 's/^ *# .*$$//' -e '/^$$/d' -e '/^#$$/d' $< | cpp -DRELEASE=$(RELEASE) -P > $@; \
	fi

# scriptfile.in must exist
all: scriptfile