Parsing and accessing variables containing '$' in Makfile - sed

Question

I have gotten myself into Makefile-hell :(
I have a file test.par containing values:
$ABC=123 ! some comment
$DEF=456 ! comment
and I have a template source file (actually in fortran, but that does not make a difference here) test/template.c:
int main(void) {
return $ABC+$DEF ;
}
and I want to set the values in the code, like a preprocessor would do. So I wrote a target in my Makefile like so:
default:
for f in test/*; do \
while read l ; do \
key="$$(echo $$l | cut -d "=" -f 1 | tr -d ' ')";\
val=$$(echo $$l | cut -d "=" -f 2 | cut -d " " -f 1);\
[[ -z "$$val" ]] && \
val=$$(echo $$l | cut -d "=" -f 2 | cut -d " " -f 2);\
echo $$key $$val;\
cp $$f $$f.out ;\
sed -i "s/$$key/$$val/g" $$f.out;\
done < test.par;\
done;
I go through every file in test/ (there are many) in the for loop and "apply" every line in test.par in the while loop.
The expected result is
int main(void) {
return 123+456 ;
}
What I get is
int main(void) {
return $ABC+456 ;
}
And now it is getting crazy: If I switch the to lines in the test.par file, I get:
int main(void) {
return 123+$DEF ;
}
If there are more lines, there no substitution at all.
What is wrong with me!!!???!!!
edit: I cannot make too many changes to the original code, so aI was hoping to solve this in the Makefile.

Answer 1

You keep reusing the original file for substitutions, so only the last one actually sticks (the result of all substitutions but the last is overwritten by the next). After
sed "s/$$key/$$val/g" $$f > $$f.out;\
put
cp "$$f.out" "$$f";\
to fix this. (Or make a working copy of $$f, if you want $$f unchanged, e.g., cp "$$f" "$$f.out" before the loop and use sed -i "s/$$key/$$val/g" "$$f.out" inside.)