Using Makefile to clean subdirectories

Question

Is it possible to perform a make clean from the parent directory which also recursively cleans all sub-directories without having to include a makefile in each sub-directory?

Answer 1

Instead of using recursion, you could shell out to find to get a list of directories and do a single iteration to generate the wildcards:

SUBDIR_ROOTS := foo bar
DIRS := . $(shell find $(SUBDIR_ROOTS) -type d)
GARBAGE_PATTERNS := *.o *~ core .depend .*.cmd *.ko *.mod.c
GARBAGE := $(foreach DIR,$(DIRS),$(addprefix $(DIR)/,$(GARBAGE_PATTERNS)))

clean:
    rm -rf $(GARBAGE)