Create directories using make file

Question

I want to create directories using makefile. My project directory is like this

+--Project      +--output      +--source        +Testfile.cpp      +Makefile   

I want to put all the objects and output into the respective output folder. I want to create folder structure which would be like this after compiling.

+--Project    +--output      +--debug (or release)        +--objs          +Testfile.o        +Testfile (my executable file)    +--source      +Testfile.cpp    +Makefile 

I tried with several options, but could not succeed. Please help me to make directories using make file. I'm posting my Makefile for your consideration.

#--------------------------------------------------------------------- # Input dirs, names, files #--------------------------------------------------------------------- OUTPUT_ROOT := output/  TITLE_NAME := TestProj   ifdef DEBUG      TITLE_NAME += _DEBUG else ifdef RELEASE     TITLE_NAME += _RELEASE endif endif   # Include all the source files here with the directory tree SOURCES := \         source/TestFile.cpp \  #--------------------------------------------------------------------- # configs #--------------------------------------------------------------------- ifdef DEBUG OUT_DIR     := $(OUTPUT_ROOT)debug CC_FLAGS    := -c -Wall else ifdef RELEASE OUT_DIR     := $(OUTPUT_ROOT)release CC_FLAGS    := -c -Wall else $(error no build type defined) endif endif  # Put objects in the output directory. OUT_O_DIR   := $(OUT_DIR)/objs  #--------------------------------------------------------------------- # settings #--------------------------------------------------------------------- OBJS = $(SOURCES:.cpp=.o) DIRS = $(subst /,/,$(sort $(dir $(OBJS)))) DIR_TARGET = $(OUT_DIR)  OUTPUT_TARGET = $(OUT_DIR)/$(TITLE_NAME)  CC_FLAGS +=     LCF_FLAGS :=   LD_FLAGS :=   #--------------------------------------------------------------------- # executables #--------------------------------------------------------------------- MD := mkdir RM := rm CC := g++  #--------------------------------------------------------------------- # rules #--------------------------------------------------------------------- .PHONY: all clean title   all: title   clean:     $(RM) -rf $(OUT_DIR)  $(DIR_TARGET):     $(MD) -p $(DIRS)  .cpp.o:      @$(CC) -c $< -o $@  $(OBJS): $(OUT_O_DIR)/%.o: %.cpp     @$(CC) -c $< -o $@  title: $(DIR_TARGET) $(OBJS) 

Answer 1

In my opinion, directories should not be considered targets of your makefile, either in technical or in design sense. You should create files and if a file creation needs a new directory then quietly create the directory within the rule for the relevant file.

If you're targeting a usual or "patterned" file, just use make's internal variable $(@D), that means "the directory the current target resides in" (cmp. with $@ for the target). For example,

$(OUT_O_DIR)/%.o: %.cpp         @mkdir -p $(@D)         @$(CC) -c $< -o $@  title: $(OBJS) 

Then, you're effectively doing the same: create directories for all $(OBJS), but you'll do it in a less complicated way.

The same policy (files are targets, directories never are) is used in various applications. For example, git revision control system doesn't store directories.

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Note: If you're going to use it, it might be useful to introduce a convenience variable and utilize make's expansion rules.

dir_guard=@mkdir -p $(@D)  $(OUT_O_DIR)/%.o: %.cpp         $(dir_guard)         @$(CC) -c $< -o $@  $(OUT_O_DIR_DEBUG)/%.o: %.cpp         $(dir_guard)         @$(CC) -g -c $< -o $@  title: $(OBJS)