make-04.html

unix make 文档

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另外需要注意：在</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">Linux</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">（</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">unix</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">）中，以波浪线“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">~</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”开始的文件名有特殊含义。单独使用它或者其后跟一个斜线（</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">~/</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">），代表了当前用户的宿主目录（在</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">shell</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">下可以通过命令“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">echo 
~(~\)</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”来查看）。例如“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">~/bin</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”代表“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">/home/username/bin/</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”（当前用户宿主目录下的</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">bin</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">目录）。波浪线之后跟一个单词（</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">~word</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">），代表由这个“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">word</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”所指定的用户的宿主目录。例如“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">~john/bin</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”就是代表用户</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">john</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">的宿主目录下的</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">bin</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">目录。</span></p>
<span style="font-size: 12.0pt; font-family: 楷体_GB2312; color: black">在一些系统中（像</span><span lang="EN-US" style="font-size: 12.0pt; font-family: Arial; color: black">MS-DOS</span><span style="font-size: 12.0pt; font-family: 楷体_GB2312; color: black">和</span><span lang="EN-US" style="font-size: 12.0pt; font-family: Arial; color: black">MS-Windows</span><span style="font-size: 12.0pt; font-family: 楷体_GB2312; color: black">），用户没有各自的宿主目录，此情况下可通过设置环境变量“</span><span lang="EN-US" style="font-size: 12.0pt; font-family: Arial; color: black">HOME</span><span style="font-size: 12.0pt; font-family: 楷体_GB2312; color: black">”来模拟。</span><h3><a name="_gnu_make_4.4.1"><span lang="en-us">4</span><span lang="EN-US">.4.1 </span><span style="font-family: 楷体_GB2312">统配符使用举例</span></a></h3>
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本节开始已经提到过，通配符可被用在规则的命令中，它是在命令被执行时由</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">shell</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">进行处理。例如</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">Makefile</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">的清空过程文件规则：</span></p>
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&nbsp;</span></p>
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<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">clean:</span></i></b></p>
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<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">rm -f *.o</span></i></b></p>
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&nbsp;</span></p>
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通配符也可以用在规则的依赖文件名中。看看下面这个例子。执行“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">make 
print</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”，执行的结果是打印当前工作目录下所有的在上一次打印以后被修改过的“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">.c</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”文件。</span></p>
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<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">print: *.c</span></i></b></p>
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<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">lpr -p $?</span></i></b></p>
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<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">touch print</span></i></b></p>
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&nbsp;</span></p>
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两点说明：</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">1.
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上述的规则中目标“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">print</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”时一个空目标文件。（当前目录下存在一个文件“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">print</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”，但我们不关心它的实际内容，此文件的作用只是记录最后一次执行此规则的时间。</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">2.
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自动环变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">$?</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”在这里表示依赖文件列表中被改变过的所有文件。</span></p>
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变量定义中使用的通配符不会被统配处理（因此在变量定义中不能使用通配符，否则在某些情况下会出现非预期的结果，下一小节将会详细讨论）。在</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">Makefile</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">有这样一个变量定义：“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial">objects 
= *.o</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”。它表示变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">objects</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”的值是字符串“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">*.o</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”（并不是期望的空格分开的</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">.o</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">文件列表）。当需要变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">objects</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”代表所有</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">.o</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">文件列表示，需要使用函数“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">wildcard</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”（</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">objects 
= $(wildcar *.o)</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">）。</span></p>
<h3><a name="_gnu_make_4.4.2"><span lang="en-us">4</span><span lang="EN-US">.4.2 </span><span style="font-family: 楷体_GB2312">通配符存在的缺陷</span></a></h3>
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在上一小节提到过变量定义时使用通配符可能在某些情况下会导致意外的结果。本小节将对此进行详细地分析和讨论。书写</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">Makefile</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">时，可能存在这种不正确的使用通配符的方法。这种看似正确的方式产生的结果可能产生非期望的结果。例如在你的</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">Makefile</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">中，期望能够根据所有的</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">.o</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">文件生成可执行文件“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">foo</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”。实现如下：</span></p>
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&nbsp;</span></p>
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<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">objects = *.o</span></i></b></p>
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<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">&nbsp;</span></i></b></p>
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<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">foo : 
$(objects)</span></i></b></p>
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<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">cc -o foo $(CFLAGS) 
$(objects)</span></i></b></p>
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&nbsp;</span></p>
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这里变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">objects</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”的值是一个字符串“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black"