The make's intro from hckweb

make's Introduction

What is this?

A tutorial of cool Makefile trick to deal with a messy source code!

The source tree

❯ tree
.
├── a
│   └── b
│       ├── c
│       │   └── d
│       │       ├── e
│       │       │   └── main.c
│       │       └── f
│       │           └── include_me.h
│       └── donothing.c
├── LICENSE
├── Makefile
└── README.md

6 directories, 6 files

Notice the following:

the main.c is burried somewhere deep.
the header file and other source files are also burried somewhere very deep!

Try this

❯ make
gcc -I./a/b/c/d/f/ -c a/b/c/d/e/main.c -o a/b/c/d/e/main.o
gcc -I./a/b/c/d/f/ -c a/b/donothing.c -o a/b/donothing.o
gcc -o main a/b/c/d/e/main.o a/b/donothing.o

make does all the hard work! Then try this:

❯ ./main 
hello, world!

The Trick

Find all .c file path.
Find all directories that have the .h files.
Provide the list to compiler (gcc) to generate main

What is what in the Makefile

gibberish	description
`PROJECT`	Final output, set to `main`.
`SRC`	List of path of `.c` files.
`OBJS`	List of `.o` files (generated from `SRC`).
`INC`	List of directories that have the `.h` files.
`INC`	List of directories that have the `.h` files.
`%.o: %c`	`.o` file depends on `.c` file with same name. Eg: `foo.o` depends on `foo.c`
`$^`	All files in the dependency list.
`$@`	The target.
`.PHONY`	Make targets that don't depend on anything.

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