make-07.html

unix make 文档

<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">normal_libs =</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">&nbsp;</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">……</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">&nbsp;</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">foo: $(objects)</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">&nbsp;</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">ifeq ($(CC),gcc)</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 58.2pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">$(CC) -o foo 
$(objects) $(libs_for_gcc)</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">else</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 58.2pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">$(CC) -o foo 
$(objects) $(normal_libs)</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">endif</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">……</span></i></b></p>
<p class="MsoNormal" style="text-indent: 20.5pt">
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">&nbsp;</span></p>
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<span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">
例子中，条件语句中使用到了三个关键字：“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">ifeq</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">else</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”和“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">endif</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”。其中：</span></p>
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<span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">
1.<span style="font:7.0pt &quot;Times New Roman&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></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">ifeq</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”表示条件语句的开始，并指定了一个比较条件（相等）。之后是用圆括号括包围的、使用逗号“</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">”分割的两个参数，和关键字“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">ifeq</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”用空格分开。参数中的变量引用在进行变量值比较时被展开。“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">ifeq</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”之后就是当条件满足</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">make</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">需要执行的，条件不满足时忽略。</span></p>
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<span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">
2.<span style="font:7.0pt &quot;Times New Roman&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></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">else</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”之后就是当条件不满足时的执行部分。不是所有的条件语句都需要此部分。</span></p>
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<span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">
3.<span style="font:7.0pt &quot;Times New Roman&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></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">endif</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”表示一个条件语句的结束，任何一个条件表达式都必须以“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">endif</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”结束。</span></p>
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<span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">
通过上边的例子我们可以了解到。</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，条件表达式工作于文本级别（条件判断处理为文本级别的处理过程），条件的解析是由</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">make</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">来完成的。</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">make</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">是在读取并解析</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">时根据条件表达式忽略条件表达式中的某一个文本行，解析完成后保留的只有表达式满足条件所需要执行的文本行。上例，</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">make</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">处理条件的过程：</span></p>
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<span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">
当变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">CC</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”的值为“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">gcc</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”时，整个条件表达式等效于：</span></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">foo: $(objects)</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 58.2pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">$(CC) -o foo 
$(objects) $(libs_for_gcc)</span></i></b></p>
<p class="MsoNormal" style="text-indent: 20.5pt">
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">&nbsp;</span></p>
<p class="MsoNormal" style="text-align: justify; text-justify: inter-ideograph; text-indent: 24.0pt; line-height: 150%; text-autospace: ideograph-numeric ideograph-other">
<span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">
当变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">CC</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”值不等于“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">gcc</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”时等效于：</span></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">foo: $(objects)</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 58.2pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">$(CC) -o foo 
$(objects) $(normal_libs)</span></i></b></p>
<p class="MsoNormal" style="text-align: justify; text-justify: inter-ideograph; text-indent: 24.0pt; line-height: 150%; text-autospace: ideograph-numeric ideograph-other">
<span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">
&nbsp;</span></p>
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<span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">
上面的例子，一种更简洁实现方式：</span></p>
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<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">libs_for_gcc = 
-lgnu</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">normal_libs =</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">&nbsp;</span></i></b></p>
<p class="MsoNormal" style="text-indent: 13.85pt; margin-left: 29.95pt"><b><i>