关于Linux下对于makefile的理解
<p>什么是makefile呢？在Linux下makefile我们可以把理解为工程的编译规则。一个工程中源文件不计数，其按类型、功能、模块分别放在若干个目录中，makefile定义了一系列的规则来指定，那些文件需要先编译，那些文件需要后编译，那些文件需要重新编译，甚至于进行更复杂的功能操作，因为makefile就像一个shell脚本一样，其中也可执行操作系统的命令。</p>
<p>
makefile带来的好处就是---“自动化编译”，一旦写好，只需要一个make命令，整个工程完全自动编译，极大地提高了软件开发的效率。</p>
<p>
make命令在执行时，需要一个makefile文件，以告诉make命令要怎样去编译链接程序。只要我们makefile写的足够好，make命令会自动智能的根据当前文件自己编译所需要的文件和链接目标文件。</p>
<p>
<span><strong>makefile的规则：</strong></span></p>
<div class="jb51code">
<div>
<div class="syntaxhighlighterxhtml" id="highlighter_371413">
<div class="toolbar">
<span>?</span>
</div>
<table border="0" cellpadding="0" cellspacing="0"><tbody><tr>
<td class="gutter">
<div class="line number1 index0 alt2">
1</div>
<div class="line number2 index1 alt1">
2</div>
<div class="line number3 index2 alt2">
3</div>
<div class="line number4 index3 alt1">
4</div>
<div class="line number5 index4 alt2">
5</div>
</td>
<td class="code">
<div class="container">
<div class="line number1 index0 alt2">
<code class="xhtml plain">target：prerequisites</code>
</div>
<div class="line number2 index1 alt1">
</div>
<div class="line number3 index2 alt2">
<code class="xhtml plain"> command</code>
</div>
<div class="line number4 index3 alt1">
</div>
<div class="line number5 index4 alt2">
<code class="xhtml plain">.......................</code>
</div>
</div>
</td>
</tr></tbody></table>
</div>
</div>
<div class="codetool" id="codetool">
<div class="code_n">
<textarea></textarea>
</div>
</div>
</div>
<p>
target是目标文件，prerequisites就是要生成target所需要的文件或是目标。command就是make需要执行的命令。这是一个文件依赖关系，也就是说，target这一个或多个的目标文件依赖于prerequisites中的文件，其生成规则定义在command中。如果prerequisites中如果有一个以上的文件比target文件内容要新的话，command所定义的文件就会被执行。这就是makefile最核心的内容。</p>
<p>
<span><strong>举个栗子：</strong></span></p>
<p>
先准备三个文件：file1.c,file2.c,file2.h</p>
<p>
<span><strong>file1.c:</strong></span></p>
<div class="jb51code">
<div>
<div class="syntaxhighlighterxhtml" id="highlighter_484495">
<div class="toolbar">
<span>?</span>
</div>
<table border="0" cellpadding="0" cellspacing="0"><tbody><tr>
<td class="gutter">
<div class="line number1 index0 alt2">
1</div>
<div class="line number2 index1 alt1">
2</div>
<div class="line number3 index2 alt2">
3</div>
<div class="line number4 index3 alt1">
4</div>
<div class="line number5 index4 alt2">
5</div>
<div class="line number6 index5 alt1">
6</div>
<div class="line number7 index6 alt2">
7</div>
<div class="line number8 index7 alt1">
8</div>
<div class="line number9 index8 alt2">
9</div>
<div class="line number10 index9 alt1">
10</div>
<div class="line number11 index10 alt2">
11</div>
</td>
<td class="code">
<div class="container">
<div class="line number1 index0 alt2">
<code class="xhtml plain">#include<</code><code class="xhtml keyword">iostream</code><code class="xhtml plain">></code>
</div>
<div class="line number2 index1 alt1">
</div>
<div class="line number3 index2 alt2">
<code class="xhtml plain">int main()</code>
</div>
<div class="line number4 index3 alt1">
</div>
<div class="line number5 index4 alt2">
<code class="xhtml plain">{</code>
</div>
<div class="line number6 index5 alt1">
</div>
<div class="line number7 index6 alt2">
<code class="xhtml plain">file2printf();</code>
</div>
<div class="line number8 index7 alt1">
</div>
<div class="line number9 index8 alt2">
<code class="xhtml plain">return 0;</code>
</div>
<div class="line number10 index9 alt1">
</div>
<div class="line number11 index10 alt2">
<code class="xhtml plain">}</code>
</div>
</div>
</td>
</tr></tbody></table>
</div>
</div>
<div class="codetool" id="codetool">
<div class="code_n">
<textarea></textarea>
</div>
</div>
</div>
<p>
<span><strong>file2.h:</strong></span></p>
<div class="jb51code">
<div>
<div class="syntaxhighlighterxhtml" id="highlighter_39598">
<div class="toolbar">
<span>?</span>
</div>
<table border="0" cellpadding="0" cellspacing="0"><tbody><tr>
<td class="gutter">
<div class="line number1 index0 alt2">
1</div>
<div class="line number2 index1 alt1">
2</div>
<div class="line number3 index2 alt2">
3</div>
<div class="line number4 index3 alt1">
4</div>
<div class="line number5 index4 alt2">
5</div>
<div class="line number6 index5 alt1">
6</div>
<div class="line number7 index6 alt2">
7</div>
<div class="line number8 index7 alt1">
8</div>
<div class="line number9 index8 alt2">
9</div>
<div class="line number10 index9 alt1">
10</div>
<div class="line number11 index10 alt2">
11</div>
<div class="line number12 index11 alt1">
12</div>
<div class="line number13 index12 alt2">
13</div>
<div class="line number14 index13 alt1">
14</div>
<div class="line number15 index14 alt2">
15</div>
<div class="line number16 index15 alt1">
16</div>
<div class="line number17 index16 alt2">
17</div>
<div class="line number18 index17 alt1">
18</div>
<div class="line number19 index18 alt2">
19</div>
</td>
<td class="code">
<div class="container">
<div class="line number1 index0 alt2">
<code class="xhtml plain">#ifndef FILE2_H_</code>
</div>
<div class="line number2 index1 alt1">
</div>
<div class="line number3 index2 alt2">
<code class="xhtml plain">#define FILE2_H_</code>
</div>
<div class="line number4 index3 alt1">
</div>
<div class="line number5 index4 alt2">
<code class="xhtml plain">void file2printf();</code>
</div>
<div class="line number6 index5 alt1">
</div>
<div class="line number7 index6 alt2">
<code class="xhtml plain">#endif</code>
</div>
<div class="line number8 index7 alt1">
</div>
<div class="line number9 index8 alt2">
<code class="xhtml plain">file2.c</code>
</div>
<div class="line number10 index9 alt1">
</div>
<div class="line number11 index10 alt2">
<code class="xhtml plain">#include"file2.h"</code>
</div>
<div class="line number12 index11 alt1">
</div>
<div class="line number13 index12 alt2">
<code class="xhtml plain">void file2printf()</code>
</div>
<div class="line number14 index13 alt1">
</div>
<div class="line number15 index14 alt2">
<code class="xhtml plain">{</code>
</div>
<div class="line number16 index15 alt1">
</div>
<div class="line number17 index16 alt2">
<code class="xhtml plain">printf("hello world!\n");</code>
</div>
<div class="line number18 index17 alt1">
</div>
<div class="line number19 index18 alt2">
<code class="xhtml plain">}</code>
</div>
</div>
</td>
</tr></tbody></table>
</div>
</div>
<div class="codetool" id="codetool">
<div class="code_n">
<textarea></textarea>
</div>
</div>
</div>
<p>
那么它的makefile怎么写呢？（makefile文件和文件在同一目录下）</p>
<p>
test:file1.o file2.o //test依赖file1.o和file2.o两个目标文件</p>
<p>
gcc -c file1.o file2.o -o test //编译出test可执行文件，-o 表示指定的目标文件名</p>
<p>
file1.o:file1.c file2.h //编译出file1.o文件，file1.o依赖于file1.c和file2.h,-c表示GCC只把给他的文件编译成目标文件 </p>
<p>
gcc -c file1.c -o file1.o</p>
<p>
file2.o:file2.c file2.h //这两句与上两句相同</p>
<p>
gcc -c file2.c -o file2.o</p>
<p>
.PHONY:clean</p>
<p>
<strong>clean:</strong></p>
<p>
rm -rf* .o test //当输入make clean命令时，就会删除所有的.o文件和test文件了</p>
<p>
<strong><span>注意：每个命令行之前都必须有tab符号。</span></strong></p>
<p>
这是简单的makefile的写法，其实makefile还有很多的功能注意点值得学习。大家可以下去自行学习</p>
<p>
以上这篇关于Linux下对于makefile的理解就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。</p>
頁:
[1]