make wildcard subdirectory targets

Question

I have a \"lib\" directory in my applications main directory, which contains an arbitrary number of subdirectories, each having its own Makefile.

I would like to have a

Answer 1

The following will work with GNU make:

LIBS=$(wildcard lib/*)
all: $(LIBS)
.PHONY: force
$(LIBS): force
  cd $@ && pwd

If there might be something other than directories in lib, you could alternatively use:

LIBS=$(shell find lib -type d)

To address the multiple targets issue, you can build special targets for each directory, then strip off the prefix for the sub-build:

LIBS=$(wildcard lib/*)
clean_LIBS=$(addprefix clean_,$(LIBS))
all: $(LIBS)
clean: $(clean_LIBS)
.PHONY: force
$(LIBS): force
  echo make -C $@
$(clean_LIBS): force
  echo make -C $(patsubst clean_%,%,$@) clean