Copy files recursively with GNU Make

Question

I got a directory where store my project assets, say:

+-- assets
|   +-- styles
|   |   +-- child
|   |   |   +-- child.css
|   |   +-- main.css
|   +-- font.ttf
|   +-- image.png

As you can see, they are several file types (this is only a sample, may have many more types) and the tree depth may vary.

How can i copy all this files into a single (flat) location? Something like this:

+-- assets
|   +-- child.css
|   +-- font.ttf
|   +-- image.png
|   +-- main.css

I tried use pattern rules but i'm pretty new in GNU Make, so nothing seems to work.

I got the recursive list of source files using the Bash globstar functionality, and modify it by Make's string manipulation functions:

BR_ASSETS := /home/user/project/assets/
BR_APP_ASSETS := /home/user/project/build/assets/

SOURCES := $(shell ls $(BR_ASSETS)**/*.*)
TARGETS := $(addprefix $(BR_APP_ASSETS),$(notdir $(SOURCES)))

What next?

Many thanks in advance.

Answer 1

all:
.PHONY: all

BR_ASSETS := /home/user/project/assets/
BR_APP_ASSETS := /home/user/project/build/assets/

SOURCES := $(shell find $(BR_ASSETS) -type f)
$(info SOURCES=$(SOURCES))
TARGETS := $(addprefix $(BR_APP_ASSETS),$(notdir $(SOURCES)))

# Generate rules to map sources into targets
$(foreach s,$(SOURCES),$(foreach t,$(filter %$(notdir $s),$(TARGETS)),$(info New rule: $t: $s)$(eval $t: $s)))

# All targets have the same recipe.
$(TARGETS):; $(if $(wildcard $(@D)),,mkdir -p $(@D) &&) cp $^ $@

all: $(TARGETS)
clean:; rm -rf $(BR_APP_ASSETS)
.PHONY: clean

Environment before running this Makefile:

$ find /home/user/project
/home/user/project
/home/user/project/assets
/home/user/project/assets/font.ttf
/home/user/project/assets/img.png
/home/user/project/assets/styles
/home/user/project/assets/styles/child
/home/user/project/assets/styles/child/child.css
/home/user/project/assets/styles/main.css
/home/user/project/build

Run this Makefile:

$ make -f Makefile.sample
SOURCES=/home/user/project/assets/font.ttf /home/user/project/assets/img.png /home/user/project/assets/styles/child/child.css /home/user/project/asset
s/styles/main.css
New rule: /home/user/project/build/assets/font.ttf: /home/user/project/assets/font.ttf
New rule: /home/user/project/build/assets/img.png: /home/user/project/assets/img.png
New rule: /home/user/project/build/assets/child.css: /home/user/project/assets/styles/child/child.css
New rule: /home/user/project/build/assets/main.css: /home/user/project/assets/styles/main.css
mkdir -p /home/user/project/build/assets && cp /home/user/project/assets/font.ttf /home/user/project/build/assets/font.ttf
cp /home/user/project/assets/img.png /home/user/project/build/assets/img.png
cp /home/user/project/assets/styles/child/child.css /home/user/project/build/assets/child.css
cp /home/user/project/assets/styles/main.css /home/user/project/build/assets/main.css

Environment after running this Makefile:

$ find /home/user/project
/home/user/project
/home/user/project/assets
/home/user/project/assets/font.ttf
/home/user/project/assets/img.png
/home/user/project/assets/styles
/home/user/project/assets/styles/child
/home/user/project/assets/styles/child/child.css
/home/user/project/assets/styles/main.css
/home/user/project/build
/home/user/project/build/assets
/home/user/project/build/assets/child.css
/home/user/project/build/assets/font.ttf
/home/user/project/build/assets/img.png
/home/user/project/build/assets/main.css