前些日子又搞起了OpenWRT,之前一直只是使用shell或者Lua实现自己的想法,随着C渐渐使用的顺畅了,打算学习下OpenWRT上程序的编写以及交叉编译。
首先列下目录结构
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lee@ubuntu:~/OpenWrt-SDK-ar71xx-for-linux-i486-gcc-4.6-linaro_uClibc-0.9.33.2/package$ tree
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.
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|-- hiOpenWRT
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| |-- Makefile
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| `-- src
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| |-- hiOpenwrt.c
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| `-- Makefile
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|-- Makefile
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`-- rules.mk
这是在OpenWRT-SDK/package下的文件结构,
需要自己建的目录有hiOpenwrt/ 和hiOpenwrt/src/ ;
需要自己建的文件有:
src下的hiOpenwrt.c
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#include <stdlib.h>
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#include <stdio.h>
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int main(void){
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printf("Hi,OpenWRT!\n");
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return 0;
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}
src下Makefile:src下Makefile:
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# build hiOpenwrt executable when user executes "make"
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hiOpenwrt: hiOpenwrt.o
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$(CC) $(LDFLAGS) hiOpenwrt.o -o hiOpenwrt
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hiOpenwrt.o: hiOpenwrt.c
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$(CC) $(CFLAGS) -c hiOpenwrt.c
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#remove object files and executable when user executes "make clean"
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clean:
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rm *.o hiOpenwrt
当然,在hiOpenwrt/Makefile也需要写,只不过这个要求比较多,格式如下:
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#-----官方文档如下
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This is the OpenWrt SDK. It contains a stripped-down version of the buildroot. You can use it to test/develop packages without having to compile your own toolchain or any of the libraries included with OpenWrt.
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To use it, just put your buildroot-compatible package directory in the subdir 'package/' and run 'make' from this directory.
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#------ OPENWRT集成非官方包之Makefile规则
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include $(TOPDIR)/rules.mk
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PKG_NAME:=[软件包名字 和文件夹名称一样]
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PKG_VERSION:=[软件包版本 自己写个]
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PKG_RELEASE:=1
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PKG_BUILD_DIR := $(BUILD_DIR)/$(PKG_NAME)
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include $(INCLUDE_DIR)/package.mk
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define Package/$(PKG_NAME)
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SECTION:=utils
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CATEGORY:=[软件包在menuconfig里的位置 比如Base system]
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DEPENDS:=[依赖包 两个之间通过空格分隔 前面加+为默认显示 选中该软件包自动选中依赖包 不加+为默认不显示 选中依赖包才显示]
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TITLE:=[标题]
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PKGARCH:=[平台 比如ar71xx 全部写all]
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MAINTAINER:=[作者]
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endef
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define Package/$(PKG_NAME)/description
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[软件包简介]
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endef
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#非本目录下的源码文件, 拷贝到此相应目录下.
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# 如../../xucommon/xucommon.c, 则将 xucommon.c 拷贝到此目录下的源码的 ../../
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define Build/Prepare
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mkdir -p $(PKG_BUILD_DIR)
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$(CP) ./src/* $(PKG_BUILD_DIR)/
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endef
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define Build/Configure
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endef
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define Build/Compile
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endef
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define Package/$(PKG_NAME)/conffiles
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[升级时保留文件/备份时备份文件 一个文件一行]
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endef
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define Package/$(PKG_NAME)/install
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$(CP) ./files/* $(1)/
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endef
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define Package/$(PKG_NAME)/preinst
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[安装前执行的脚本 记得加上#!/bin/sh 没有就空着]
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#!/bin/sh
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uci -q batch <<-EOF >/dev/null
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delete ucitrack.@aria2[-1]
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add ucitrack aria2
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set ucitrack.@aria2[-1].init=aria2
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commit ucitrack
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EOF
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exit 0
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endef
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define Package/$(PKG_NAME)/postinst
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[安装后执行的脚本 记得加上#!/bin/sh 没有就空着]
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#!/bin/sh
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rm -f /tmp/luci-indexcache
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exit 0
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endef
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Package/$(PKG_NAME)/prerm
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[删除前执行的脚本 记得加上#!/bin/sh 没有就空着]
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endef
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Package/$(PKG_NAME)/postrm
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[删除后执行的脚本 记得加上#!/bin/sh 没有就空着]
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endef
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$(eval $(call BuildPackage,$(PKG_NAME)))
自己的hiOpenwrt的Makefile自己的hiOpenwrt的Makefile
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##############################################
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# OpenWrtMakefile for hiOpenwrt program
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#
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#
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# Most ofthe variables used here are defined in
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# theinclude directives below. We just need to
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# specifya basic description of the package,
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# whereto build our program, where to find
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# thesource files, and where to install the
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# compiled program on the router.
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#
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# Be verycareful of spacing in this file.
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# Indentsshould be tabs, not spaces, and
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# thereshould be no trailing whitespace in
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# linesthat are not commented.
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#
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##############################################
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include $(TOPDIR)/rules.mk
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# Nameand release number of this package
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PKG_NAME:=hiOpenWRT
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PKG_RELEASE:=1
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# Thisspecifies the directory where we're going to build the program.
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# Theroot build directory, $(BUILD_DIR), is by default the build_mipsel
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#directory in your OpenWrt SDK directory
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PKG_BUILD_DIR:= $(BUILD_DIR)/$(PKG_NAME)
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include $(INCLUDE_DIR)/package.mk
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# Specifypackage information for this program.
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# Thevariables defined here should be self explanatory.
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# If youare running Kamikaze, delete the DESCRIPTION
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#variable below and uncomment the Kamikaze define
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# directivefor the description below
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define Package/$(PKG_NAME)
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SECTION:=utils
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CATEGORY:=Utilities
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TITLE:=hiOpenwrt-- prints a snarky message
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endef
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# Specifywhat needs to be done to prepare for building the package.
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# In ourcase, we need to copy the source files to the build directory.
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# This isNOT the default. The default uses thePKG_SOURCE_URL and the
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#PKG_SOURCE which is not defined here to download the source from the web.
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# Inorder to just build a simple program that we have just written, it is
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# mucheasier to do it this way.
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define Build/Prepare
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mkdir -p $(PKG_BUILD_DIR)
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$(CP) ./src/* $(PKG_BUILD_DIR)/
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endef
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# We donot need to define Build/Configure or Build/Compile directives
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# Thedefaults are appropriate for compiling a simple program such as this one
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# Specifywhere and how to install the program. Since we only have one file,
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# thehelloworld executable, install it by copying it to the /bin directory on
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# therouter. The $(1) variable represents the root directory on the router running
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#OpenWrt. The $(INSTALL_DIR) variable contains a command to prepare the install
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#directory if it does not already exist. Likewise $(INSTALL_BIN) contains the
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# commandto copy the binary file from its current location (in our case the build
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#directory) to the install directory.
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define Package/$(PKG_NAME)/install
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$(INSTALL_DIR) $(1)/bin
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$(INSTALL_BIN) $(PKG_BUILD_DIR)/hiOpenwrt $(1)/bin/
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endef
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# Thisline executes the necessary commands to compile our program.
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# Theabove define directives specify all the information needed, but this
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# linecalls BuildPackage which in turn actually uses this information to
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# build apackage.
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$(eval $(call BuildPackage,$(PKG_NAME)))
生成ipk的命令:
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make package/hiOpenWRT/compile V=s
加上V=s的目的是为了详细打印。
生成出来的ipk文件将在bin/ar71xx/packages/下,同时,也可以在build_dir/ build_dir/下找到可执行文件以及源码。
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lee@ubuntu:~/OpenWrt-SDK-ar71xx-for-linux-i486-gcc-4.6-linaro_uClibc-0.9.33.2$ tree | head -n 20
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.
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|-- bin
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| |-- ar71xx
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| | `-- packages
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| | `-- hiOpenWRT_1_ar71xx.ipk
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| `-- packages
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|-- build_dir
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| `-- build_dir
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| `-- hiOpenWRT
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| |-- hiOpenwrt
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| |-- hiOpenwrt.c
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| |-- hiOpenwrt.o
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| |-- ipkg-ar71xx
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| | `-- hiOpenWRT
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| | |-- bin
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| | | `-- hiOpenwrt
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| | `-- CONTROL
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| | `-- control
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| `-- Makefile
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|-- Config.in
一点总结:
目录结构很重要,如果目录结构不正确,那么Openwrt是不可能正确编译出ipk的。
在学习编译过程中出现了很多处错误,最让我头疼的是Makefile的格式,这部分很容易错误而编译失败。
Makefile编写规则:
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target ... : prerequisites ...
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command
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...
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...
target也就是一个目标文件,可以是Object File,也可以是执行文件。还可以是一个标签
(Label),对于标签这种特性,在后续的“伪目标”章节中会有叙述。
prerequisites就是,要生成那个target所需要的文件或是目标。
command也就是make需要执行的命令。(任意的Shell命令)
这是一个文件的依赖关系,也就是说,target这一个或多个的目标文件依赖于prerequisi
tes中的文件,其生成规则定义在command中。说白一点就是说,prerequisites中如果有一个以上的文件比target文件要新的话,command所定义的命令就会被执行。这就是 Makefile的规则。也就是Makefile中最核心的内容。
参考资料
http://www.cnblogs.com/laojie4321/archive/2012/03/27/2420241.html
http://blog.chinaunix.net/uid-27194309-id-3432651.html
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