Create directories using make file

Question

I\'m a very new to makefiles and i want to create directories using makefile. My project directory is like this

+--Project  
   +--output  
   +--source  
           


        

Answer 1

OS independence is critical for me, so mkdir -p is not an option. I created this series of functions that use eval to create directory targets with the prerequisite on the parent directory. This has the benefit that make -j 2 will work without issue since the dependencies are correctly determined.

# convenience function for getting parent directory, will eventually return ./
#     $(call get_parent_dir,somewhere/on/earth/) -> somewhere/on/
get_parent_dir=$(dir $(patsubst %/,%,$1))

# function to create directory targets.
# All directories have order-only-prerequisites on their parent directories
# https://www.gnu.org/software/make/manual/html_node/Prerequisite-Types.html#Prerequisite-Types
TARGET_DIRS:=
define make_dirs_recursively
TARGET_DIRS+=$1
$1: | $(if $(subst ./,,$(call get_parent_dir,$1)),$(call get_parent_dir,$1))
    mkdir $1
endef

# function to recursively get all directories 
#     $(call get_all_dirs,things/and/places/) -> things/ things/and/ things/and/places/
#     $(call get_all_dirs,things/and/places) -> things/ things/and/
get_all_dirs=$(if $(subst ./,,$(dir $1)),$(call get_all_dirs,$(call get_parent_dir,$1)) $1)

# function to turn all targets into directories
#     $(call get_all_target_dirs,obj/a.o obj/three/b.o) -> obj/ obj/three/
get_all_target_dirs=$(sort $(foreach target,$1,$(call get_all_dirs,$(dir $(target)))))

# create target dirs
create_dirs=$(foreach dirname,$(call get_all_target_dirs,$1),$(eval $(call make_dirs_recursively,$(dirname))))

TARGETS := w/h/a/t/e/v/e/r/things.dat w/h/a/t/things.dat

all: $(TARGETS)

# this must be placed after your .DEFAULT_GOAL, or you can manually state what it is
# https://www.gnu.org/software/make/manual/html_node/Special-Variables.html
$(call create_dirs,$(TARGETS))

# $(TARGET_DIRS) needs to be an order-only-prerequisite
w/h/a/t/e/v/e/r/things.dat: w/h/a/t/things.dat | $(TARGET_DIRS)
    echo whatever happens > $@

w/h/a/t/things.dat: | $(TARGET_DIRS)
    echo whatever happens > $@

For example, running the above will create:

$ make
mkdir w/
mkdir w/h/
mkdir w/h/a/
mkdir w/h/a/t/
mkdir w/h/a/t/e/
mkdir w/h/a/t/e/v/
mkdir w/h/a/t/e/v/e/
mkdir w/h/a/t/e/v/e/r/
echo whatever happens > w/h/a/t/things.dat
echo whatever happens > w/h/a/t/e/v/e/r/things.dat