Makefile overview

What is makefile. How to write a makefile.

Ref: https://opensource.com/article/18/8/what-how-makefile

What is makefile

A makefile is a file containing a set of directives used by a make build automation tool to generate a target/goal.

You may have used make to compile a program from source code.

How to write makefile

To summarize, below is the syntax of a typical rule:

1
2

target: prerequisites
<TAB> recipe

As an example, a target might be a binary file that depends on prerequisites (source files). On the other hand, a prerequisite can also be a target that depends on other dependencies:

1
2
3
4
5

final_target: sub_target final_target.c
        Recipe_to_create_final_target

sub_target: sub_target.c
        Recipe_to_create_sub_target

It is not necessary for the target and prerequisites to be a file; it could be just a name for the recipe, as in our example. We call these “phony targets.”

Example

1
2
3
4
5
6
7
8

run: test
	./test

test: test.o
	g++ test.o -o test

test.o: test.cc
	g++ -std=c++11 -c test.cc