---
title: Makefile
layout: default
---

### Var assignment

    uglify = $(uglify)        # assignment
    compressor := $(uglify)   # lazy assignment
    prefix ?= /usr/local      # safe assignment

### Magic variables

    out.o: src.c src.h
      $@   - "out.o" (target)
      $<   - "src.c" (first prerequisite)
      $^   - "src.c src.h" (all prerequisites)

    %.o: %.c
      $%   - target member name ("foo" in "foo.c")

    also:
      $+   - prerequisites (all, with duplication)
      $?   - prerequisites (new ones)
      $|   - prerequisites (order-only?)
      $*   - basename without extension of the target (?)

      $(@D) - target directory

### Command prefixes

    -    Ignore errors
    @    Don't print command
    +    Run even if Make is in 'don't execute' mode

    build:
        @echo "compiling"
        -gcc $< $@

    -include .depend

### Find files

    js_files  := $(wildcard test/*.js)
    all_files := $(shell find images -name "*")

### Substitutions

    file     = $(SOURCE:.cpp=.o)   # foo.cpp => foo.o
    outputs  = $(files:src/%.coffee=lib/%.js)

    outputs  = $(patsubst %.c, %.o, $(wildcard *.c))
    assets   = $(patsubst images/%, assets/%, $(wildcard images/*))

### More functions

    $(strip $(string_var))

    $(filter %.less, $(files))
    $(filter-out %.less, $(files))

### Building files

    %.o: %.c
      ffmpeg -i $< > $@   # Input and output
      foo $^

### Includes

    -include foo.make

### Options

    make
      -e, --environment-overrides
      -B, --always-make
      -s, --silent

      -j, --jobs=N   # parallel processing

### Conditionals

     foo: $(objects)
     ifeq ($(CC),gcc)
             $(CC) -o foo $(objects) $(libs_for_gcc)
     else
             $(CC) -o foo $(objects) $(normal_libs)
     endif