FILES := $(wildcard *.txt) $(wildcard */*.txt) $(wildcard */*/*.txt)

all: setup test

setup:
	echo "root file1" > file1.txt
	mkdir -p sub1
	echo "sub1 file2" > sub1/file2.txt
	echo "sub1 file3" > sub1/file3.txt
	mkdir -p sub2
	echo "sub2 file4" > sub2/file4.txt
	echo "sub2 file5" > sub2/file5.txt

test:
	make print_files

print_files: $(FILES)
	cat $(FILES)