What is it?

• What is make?
  • It is a program created by GNU (GNU Compiler Collection)
  • make is an automation program that optimizes terminal processes by having a “script” of commands to be executed, which are predefined in the mandatory Makefile file.
• Why is it useful?
  • Because it can reduce the entire compilation process (or other terminal commands) to a single word. Avoids typing long commands repeatedly in the terminal. It also has its own logic in the syntax (like target), preventing mistakes caused by lack of attention.

Makefile Syntax

The Makefile has its writing rules, just like standard languages such as C, C++, Python...

Therefore, it has an expected writing pattern.

It has basic elements that can relate to each other, generating the “way make will understand.”

Elements:

• / tells make to continue reading on the next line, equivalent to \\n

• @ hidden command: executes the entire command line but does not show the command itself in the terminal

• $ accesses the value of a variable declared inside the Makefile

• $$ accesses the value of a variable declared in the terminal environment, not inside the Makefile

• <name>: declares a command <name>, which after : will be interpreted as an “executable,” meaning that when you run make <name>, it will execute <name>

• /target/ comes after <name>: and serves as identification of what make will look for. For example, setting an automation rule like: automation: main.c

  make has three possible scenarios:

  • No target in the directory: Error
  • Target present in the directory: executes command <automation>
  • Target present but with the same timestamp as last <automation> execution:
    • If file exists but was not modified (timestamp1 == timestamp2), does nothing
    • If file exists but was modified (timestamp1 != timestamp2), executes <automation> again

• = is like declaring a variable... e.g., int i == 'i='

• .PHONY defines a command by itself, meaning a command without any target, executed simply by passing its own <name>

Example:

makefile
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.PHONY: first_make

first_make:
    clear

Meaning make will always execute first_make regardless of target checks.