How to create and use Makefiles

Create Makefile

Rule

The shape of a rule:

<target> : <dependency 1> <dependency 2>
	<command>

Target can be a name of a file or action.
Dependency is a file used as input to create the target. It can also be an action that will run before the command.
Command is an action that make carries out. A rule may have more than one command, each on its own line. Please note: you need to put a tab character at the beginning of every command line! This is an obscurity that catches the unwary.

.PHONY

“A phony target is one that is not really the name of a file; rather it is just a name for a recipe to be executed when you make an explicit request. There are two reasons to use a phony target: to avoid a conflict with a file of the same name, and to improve performance.”

.PHONY: build
build:
	build stuff.js

Variables

You can define variables as recursively expanded variable or simply expanded variable

Is recommended to use := because it will make the code more predictable and easier to understand.

Recursively expanded variable =

The recursively expanded variable will expand everything every time it’s called.

first = $(second)
second = $(last)
last = done

echo $(first) # done

Simply expanded variable :=

Behaves more like a variable in any programming language. The simply expanded variable is only expanded when defined.

x := foo
y := $(x) bar
x := baz

Is the same as:

y := foo bar
x := baz

Conditional variables ?=

A conditional variable will only be set if it’s not yet defined.

VERSION?=1.0.0

Makefile