make-14.html

unix make 文档

6.<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">
重建或者安装目标（一般是伪目标）的命令行可使用编译器或者相关工具程序，这些命令使用一个变量来表示。这样做的好处是：当修改一个命令时，只需要更改代表命令的变量的值就可以了。对于以下的这些命令程序：</span></p>
<p class="MsoNormal" style="text-indent: 48.0pt">
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">&nbsp;</span></p>
<p class="MsoNormal" style="margin-left:58.2pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">ar &nbsp;bison &nbsp;cc 
&nbsp;flex &nbsp;install &nbsp;ld &nbsp;ldconfig &nbsp;lex</span></i></b></p>
<p class="MsoNormal" style="margin-left:58.2pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">make &nbsp;makeinfo 
&nbsp;ranlib &nbsp;texi2dvi &nbsp;yacc</span></i></b></p>
<p class="MsoNormal" style="text-indent: 48.0pt">
<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; line-height: 150%; text-autospace: ideograph-numeric ideograph-other; margin-left: 42.0pt">
<span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">
在规则中的命令中，使用以下这些变量来代表它们：</span></p>
<p class="MsoNormal" style="text-align: justify; text-justify: inter-ideograph; line-height: 150%; text-autospace: ideograph-numeric ideograph-other; margin-left: 42.0pt">
<span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial">
&nbsp;</span></p>
<p class="MsoNormal" style="margin-left:58.2pt"><b><i>
<span lang="EN-US" style="font-size: 10.5pt; font-family: Arial">$(AR) $(BISON) 
$(CC) $(FLEX) $(INSTALL) $(LD) $(LDCONFIG)$(LEX)</span></i></b></p>
<p class="MsoNormal" style="margin-left:58.2pt"><b><i>
<span lang="EN-US" style="font-size: 10.5pt; font-family: Arial">$(MAKE) $(MAKEINFO) 
$(RANLIB) $(TEXI2DVI) $(YACC)</span></i></b></p>
<p class="MsoNormal" style="text-align: justify; text-justify: inter-ideograph; line-height: 150%; text-autospace: ideograph-numeric ideograph-other; margin-left: 42.0pt">
<span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; 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">
如果规则的命令行需要使用“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">ranlib</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”或者“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">ldconfig</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”等这些工具时，需要考虑当前的系统是否支持这些工具。当在不支持它的系统中执行包含此命令的规则时，要能够给出提示信息（提示原因是告诉用户系统不支持此命令，但不应该出现错误而退出执行）。</span></p>
<p class="MsoNormal" style="text-align: justify; text-justify: inter-ideograph; line-height: 150%; text-autospace: ideograph-numeric ideograph-other; margin-left: 18.0pt">
<span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">
对以上没有列出的其它命令，在规则的命令行使用时也应该都是通过变量的形式。例如如下的这些命令：</span></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="margin-left:58.2pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">chgrp chmod 
chown mknod</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; 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">
我们可以在</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">中为这些命令组件定义一个代表它的变量（如：</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">CHRP</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">CHMOD</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">等，在命令行中就可以使用</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">$(CHMOD)</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">来引用）。</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">
书写多系统兼容</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">时需要遵循以上的约定。如果只考虑一种系统时，以上的这些约定中可以灵活处理，比如：在命令组件的使用上，我们就可以使用这个系统独具的那些命令组件；系统支持符号链接时，我们就可以在命令行重创建一个符号链接文件。<b>对于上边的第</b></span><b><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">6</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">个约定，强烈建议大家都遵循。</span></b></p>
<h2><a name="_gnu_make_14.3"><span style="font-size: 14pt" lang="en-us"><b>1</b></span><b><span lang="EN-US" style="font-size: 14.0pt">4.3<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7.0pt; font-family: Times New Roman">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
</span></span></b><span style="font-size: 14.0pt; font-family: 楷体_GB2312">代表命令变量</span></a></h2>
<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">
在我们书写的</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">中应该讲所有的命令、选项作为变量定义，方便后期对命令的修改和对选项的修改。就是说用户可以通过修改一个变量值来重新指定所要执行的命令，或者来控制命令执行的选项、参数等。</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">
当使用变量来表示命令时，如果规则中需要使用此命令时，可通过引用代表此命令的变量来实现。例如：定义变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">CC 
= gcc</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”，规则中就可使用“</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">”来引用“</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">”。对于一些件管理器工具如“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">ln</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">rm</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">mv</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”等，可以不为它们定义变量，而直接使用。</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">
所有命令执行的参数选项也应该定义一个变量（可称为命令的选项变量）。在命令变量（代表一个命令的变量）后添加“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">FLAGS</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”来命名这个选项变量。例如：变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">CFLAGS</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”是</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">编译器（命令变量为“</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">”）的命令行选项变量；变量</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">YFLAGS</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">时命令“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">yacc</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”（命令变量为“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">YACC</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”）选项变量；变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">LDFLAGS</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”是命令“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">ld</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”（命令变量为“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">LD</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”）的选项变量等。在所有需要执行预处理的命令行应该使用变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">CCFLAGS</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”作为</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">的执行参数；同样任何需要执行链接的命令行中使用“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">LDFLAGS</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”作为命令的执行参数。</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 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">编译器的编译选项变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">CFLAGS</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”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">中通常是为编译所有的源文件提供选项变量。为编译一个特定文件增加的选项，不应包含在变量“</span><span lang="EN-US" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">CFLAGS</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">”中。编译特定文件（或者一类特定文件）时，如果需要使用特定的选项参数，可以将这些选项写在编译它所执行规则的命令行中（也可以使用</span><span lang="EN-US" style="font-family: 楷体_GB2312; font-size: 12.0pt; line-height: 150%; color: #0000FF">目标指定变量</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">或者</span><span style="font-family: 楷体_GB2312; font-size: 12.0pt; line-height: 150%; color: #0000FF">模式指定变量</span><span style="font-size: 12.0pt; line-height: 150%; font-family: 楷体_GB2312; color: black">）。例如：</span><span lang="SV" style="font-size: 12.0pt; line-height: 150%; font-family: Arial; color: black">
</span></p>
<p class="MsoNormal" style="text-indent: 20.5pt">
<span lang="SV" style="font-size: 12.0pt; font-family: Arial">&nbsp;</span></p>
<p class="MsoNormal" style="text-indent: 41.2pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">CFLAGS = -g</span></i></b></p>
<p class="MsoNormal" style="text-indent: 41.2pt"><b><i>
<span lang="EN-US" style="font-size: 12.0pt; font-family: Arial">ALL_CFLAGS = -I 
$(CFLAGS)</span></i></b></p>