makefile-build

# Makefile & Build

Write Makefiles for project automation across any language. Covers targets, dependencies, variables, pattern rules, phony targets, and using Make for Go, Python, Docker, and Node.js projects. Includes Just and Task as modern alternatives.

## When to Use

- Automating build, test, lint, deploy commands
- Defining dependencies between tasks (build before test)
- Creating a project-level task runner (consistent across team)
- Replacing long CLI commands with short memorable targets
- Managing multi-step build processes
- Any project that needs a `make build && make test && make deploy` workflow

## Makefile Basics

### Structure

```makefile
# target: prerequisites
#     recipe (MUST be indented with TAB, not spaces)

build: src/main.go
	go build -o bin/app src/main.go

test: build
	go test ./...

clean:
	rm -rf bin/

# First target is the default (runs with bare `make`)
```

### Variables

```makefile
# Simple assignment
CC = gcc
CFLAGS = -Wall -O2

# Deferred assignment (expanded when used)
FILES = $(wildcard src/*.go)

# Immediate assignment (expanded when defined)
VERSION := $(shell git describe --tags --always)

# Conditional assignment (only if not already set)
PORT ?= 8080

# Use variables
build:
	$(CC) $(CFLAGS) -o app main.c
	@echo "Version: $(VERSION)"
```

### Automatic variables

```makefile
# $@ = target name
# $< = first prerequisite
# $^ = all prerequisites
# $* = stem (pattern match)
# $(@D) = directory of target
# $(@F) = filename of target

bin/app: src/main.go src/util.go
	go build -o $@ $^
# $@ = bin/app
# $^ = src/main.go src/util.go
# $< = src/main.go

# Pattern rule
%.o: %.c
	$(CC) -c -o $@ $<
# For foo.o: $@ = foo.o, $< = foo.c, $* = foo
```

### Phony targets (not files)

```makefile
# Without .PHONY, if a file named "clean" exists, `make clean` does nothing
.PHONY: build test clean lint fmt help

build:
	go build -o bin/app ./cmd/app

test:
	go test ./...

clean:
	rm -rf bin/ dist/

# List all targets
help:
	@grep -E '^[a-...