10.htm

学习MAkefile相关的好资料

<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>$(if &lt;condition&gt;,&lt;then-part&gt;,&lt;else-part&gt;)<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>可见，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">if</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数可以包含“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">else</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>”部分，或是不含。即</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">if</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数的参数可以是两个，也可以是三个。</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;condition&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>参数是</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">if</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>的表达式，如果其返回的为非空字符串，那么这个表达式就相当于返回真，于是，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;then-part&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>会被计算，否则</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;else-part&gt;</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">会被计算。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>而</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">if</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数的返回值是，如果</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;condition&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>为真（非空字符串），那个</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;then-part&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>会是整个函数的返回值，如果</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;condition&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>为假（空字符串），那么</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;else-part&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>会是整个函数的返回值，此时如果</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;else-part&gt;</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">没有被定义，那么，整个函数返回空字串。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>所以，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;then-part&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>和</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;else-part&gt;</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">只会有一个被计算。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<H3 style="MARGIN: 13pt 0cm"><FONT size=2><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">六、</SPAN><SPAN lang=EN-US>call</SPAN><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">函数</SPAN></FONT></H3>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">call</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数是唯一一个可以用来创建新的参数化的函数。你可以写一个非常复杂的表达式，这个表达式中，你可以定义许多参数，然后你可以用</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">call</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">函数来向这个表达式传递参数。其语法是：</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>$(call &lt;expression&gt;,&lt;parm1&gt;,&lt;parm2&gt;,&lt;parm3&gt;...)<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>当</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">make</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>执行这个函数时，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;expression&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>参数中的变量，如</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">$(1)</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">$(2)</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">$(3)</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>等，会被参数</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;parm1&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;parm2&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;parm3&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>依次取代。而</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;expression&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>的返回值就是</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">call</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数的返回值。例如：</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><BR><BR><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>reverse =<SPAN style="mso-spacerun: yes">&nbsp; </SPAN>$(1) $(2)<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>foo = $(call reverse,a,b)<BR style="mso-special-character: line-break"><BR style="mso-special-character: line-break"><o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>那么，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">foo</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>的值就是“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">a b</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”。当然，参数的次序是可以自定义的，不一定是顺序的，如：</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>reverse =<SPAN style="mso-spacerun: yes">&nbsp; </SPAN>$(2) $(1)<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>foo = $(call reverse,a,b)<BR style="mso-special-character: line-break"><BR style="mso-special-character: line-break"><o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>此时的</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">foo</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>的值就是“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">b a</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<H3 style="MARGIN: 13pt 0cm"><FONT size=2><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">七、</SPAN><SPAN lang=EN-US>origin</SPAN><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">函数</SPAN><SPAN lang=EN-US><o:p></o:p></SPAN></FONT></H3>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">origin</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">函数不像其它的函数，他并不操作变量的值，他只是告诉你你的这个变量是哪里来的？其语法是：</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>$(origin &lt;variable&gt;)<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>注意，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;variable&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>是变量的名字，不应该是引用。所以你最好不要在</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;variable&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>中使用“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">$</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>”字符。</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Origin</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数会以其返回值来告诉你这个变量的“出生情况”，下面，是</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">origin</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数的返回值</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">:<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">undefined</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </SPAN></SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>如果</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;variable&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>从来没有定义过，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">origin</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数返回这个值“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">undefined</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">default</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </SPAN></SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>如果</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;variable&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>是一个默认的定义，比如“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">CC</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”这个变量，这种变量我们将在后面讲述。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">environment</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </SPAN></SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>如果</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;variable&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>是一个环境变量，并且当</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Makefile</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>被执行时，“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">-e</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”参数没有被打开。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">file</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </SPAN></SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>如果</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;variable&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>这个变量被定义在</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Makefile</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">中。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">command line</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </SPAN></SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>如果</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;variable&gt;</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">这个变量是被命令行定义的。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">override</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </SPAN></SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>如果</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;variable&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>是被</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">override</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">指示符重新定义的。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">automatic</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </SPAN></SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>如果</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;variable&gt;</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">是一个命令运行中的自动化变量。关于自动化变量将在后面讲述。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>这些信息对于我们编写</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Makefile</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>是非常有用的，例如，假设我们有一个</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Makefile</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>其包了一个定义文件</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Make.def</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>，在</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Make.def</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>中定义了一个变量“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">bletch</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>”，而我们的环境中也有一个环境变量“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">bletch</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>”，此时，我们想判断一下，如果变量来源于环境，那么我们就把之重定义了，如果来源于</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Make.def</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>或是命令行等非环境的，那么我们就不重新定义它。于是，在我们的</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Makefile</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">中，我们可以这样写：</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>ifdef bletch<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>ifeq "$(origin bletch)" "environment"<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>bletch = barf, gag, etc.<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>endif<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>endif<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>当然，你也许会说，使用</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">override</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>关键字不就可以重新定义环境中的变量了吗？为什么需要使用这样的步骤？是的，我们用</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">override</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>是可以达到这样的效果，可是</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">override</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">过于粗暴，它同时会把从命令行定义的变量也覆盖了，而我们只想重新定义环境传来的，而不想重新定义命令行传来的。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<H3 style="MARGIN: 13pt 0cm"><FONT size=2><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">八、</SPAN><SPAN lang=EN-US>shell</SPAN><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">函数</SPAN></FONT></H3>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">shell</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数也不像其它的函数。顾名思义，它的参数应该就是操作系统</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Shell</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>的命令。它和反引号“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">`</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>”是相同的功能。这就是说，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">shell</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数把执行操作系统命令后的输出作为函数返回。于是，我们可以用操作系统命令以及字符串处理命令</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">awk</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">sed</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">等等命令来生成一个变量，如：</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>contents := $(shell cat foo)<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>files := $(shell echo *.c)<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>注意，这个函数会新生成一个</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Shell</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>程序来执行命令，所以你要注意其运行性能，如果你的</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Makefile</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>中有一些比较复杂的规则，并大量使用了这个函数，那么对于你的系统性能是有害的。特别是</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Makefile</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>的隐晦的规则可能会让你的</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">shell</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">函数执行的次数比你想像的多得多。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<H3 style="MARGIN: 13pt 0cm"><FONT size=2><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">九、控制</SPAN><SPAN lang=EN-US>make</SPAN><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">的函数</SPAN></FONT></H3>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">make</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>提供了一些函数来控制</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">make</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>的运行。通常，你需要检测一些运行</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Makefile</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>时的运行时信息，并且根据这些信息来决定，你是让</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">make</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">继续执行，还是停止。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><STRONG>$(error &lt;text ...&gt;)<o:p></o:p></STRONG></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN></SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>产生一个致命的错误，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: