What do $< and $@ mean in makefiles?

Question

I have a.csv,b.csv, ... in a my docs/csv directory, I need convert each of this file to a json file.

I follow this question to wri

Answer 1

The trouble is that in this rule:

$(DESTS): $(SRCS)
    ...

every lua file depends on all csv files, which is not what I think you intend. And since $< expands to the first prerequisite, you get the same one (items.csv) for every target.

Try this:

all: $(DESTS)

scripts/data/%.lua: docs/csv/%.csv 
    echo $@
    echo $<