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 GNU make man page on Automatic Variables is extremely useful. Here's what it says:

$@

The file name of the target of the rule. If the target is an archive member, then ‘$@’ is the name of the archive file. In a pattern rule that has multiple targets (see Introduction to Pattern Rules), ‘$@’ is the name of whichever target caused the rule's recipe to be run.

$<

The name of the first prerequisite. If the target got its recipe from an implicit rule, this will be the first prerequisite added by the implicit rule (see Implicit Rules).

Incidentally, you probably want to write your make rule as a pattern rule instead:

%.lua : %.csv