Advanced Programming in the Unix Environment (APUE), 3rd Editon

Practice

Do coding yourself now! Learn real Unix/Linux system by realizing every sample.

Makefile

Make是最常用的构建工具，诞生于1977年，主要用于C语言的项目。实际上，只要某个文件有变化，就需要重新构建的项目，都可以用Make构建。

Basic Rule

Makefile文件的格式

target : prerequisites
    recipe
    …

Comments (注释)

井号#在Makefile中表示注释。

Echoing (回声)

正常情况下，make会打印每条命令，然后再执行，这就叫做回声（echoing）。在命令的前面加上@，就可以关闭回声。

test :
    @# 这是测试
    @echo TODO

Wildcard (通配符)

Makefile的通配符与Bash一致，主要有星号*, 问号？和 []。比如， *.o 表示所有后缀名为o的文件。

clean :
    rm -f *.o

Pattern Rules (模式匹配)

For example, %.c as a pattern matches any file name that ends in .c. s.%.c as a pattern matches any file name that starts with s., ends in .c and is at least five characters long. (There must be at least one character to match the %.) The substring that the % matches is called the stem. Make命令允许对文件名，进行类似正则运算的匹配，主要用到的匹配符是%。比如，假定当前目录下有 f1.c 和 f2.c 两个源码文件，需要将它们编译为对应的对象文件。

%.o : %.c

等同于

f1.o : f1.c
f2.o : f2.c

Variable and Assignments (变量和赋值)

VARIABLE = value # 在执行时扩展，允许递归扩展。
VARIABLE := value # 在定义时扩展。
VARIABLE ?= value # 只有在该变量为空时才设置值。
VARIABLE += value # 将值追加到变量的尾端。

Implicit Variables (内置变量)

AR Archive-maintaining program; default ‘ar’.
AS Program for compiling assembly files; default ‘as’.
CC Program for compiling C programs; default ‘cc’.
CFLAGS Extra flags to give to the C compiler.
LDFLAGS Extra flags to give to compilers when they are supposed to invoke the linker, ld, such as -L. Libraries (-lfoo) should be added to the LDLIBS variable instead.
LDLIBS Library flags or names given to compilers when they are supposed to invoke the linker, ld. LOADLIBES is a deprecated (but still supported) alternative to LDLIBS. Non-library linker flags, such as -L, should go in the LDFLAGS variable.

Automatic Variables (自动变量)

$@ The file name of the target of the rule.
$< The name of the first prerequisite.
$^ The names of all the prerequisites, with spaces between them.
$? The names of all the prerequisites that are newer than the target, with spaces between them.
$(@D) The directory part of the file name of the target, with the trailing slash removed. Also $(<D).
$(@F) The file-within-directory part of the file name of the target.If the value of $@ is dir/foo.o then $(@F) is foo.o. $(@F) is equivalent to $(notdir $@). Also $(<F)

Judge and Loop (判断和循环)

Makefile使用 Bash 语法，完成判断和循环。

CC = gcc

ifeq ($(CC),gcc)
    libs=$(libs_for_gcc)
else
    libs=$(normal_libs)
endif

LIST = one two three
loop :
    for  item in $(LIST); don \
        echo $$item; \
    done

Function (函数)

Makefile 还可以使用函数，格式如下:

$(function arguments)
# or
${function arguments}

Makefile提供了许多内置函数，可供调用。下面是几个常用的内置函数。

shell 函数 srcfiles := $(shell echo src/{00..99}.txt)
wildcard 函数 srcfiles := $(wildcard src/*.txt)
subst 函数 $(subst from,to,text)
patsubst函数 $(patsubst pattern,replacement,text)
替换后缀名 $(OUTPUT:.js=.min.js)

References and Links

Make 命令教程 - 阮一峰
GNU Make Manual - Official Manual
跟我一起写Makefile - 陈皓

wenchy / APUE