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unix简单的信号处理

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unix下最简单的信号处理函数是signal函数:

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#include <span style="color: #339933;">&lt;</span>signal .<span style="color: #202020;">h</span><span style="color: #339933;">&gt;</span>
<span style="color: #993333;">void</span> <span style="color: #009900;">(</span><span style="color: #339933;">*</span>signal<span style="color: #009900;">(</span><span style="color: #993333;">int</span> signo<span style="color: #339933;">,</span><span style="color: #993333;">void</span> <span style="color: #009900;">(</span><span style="color: #339933;">*</span>func<span style="color: #009900;">)</span><span style="color: #009900;">(</span><span style="color: #993333;">int</span><span style="color: #009900;">)</span><span style="color: #009900;">)</span><span style="color: #009900;">)</span><span style="color: #009900;">(</span><span style="color: #993333;">int</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>

sign参数是信号名,func是信号处理程序。

为了简化signal函数的书写,我们通常用typedef:

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<span style="color: #993333;">typedef</span> <span style="color: #993333;">void</span> signfunc<span style="color: #009900;">(</span><span style="color: #993333;">int</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>
signfunc signal<span style="color: #009900;">(</span><span style="color: #993333;">int</span><span style="color: #339933;">,</span>signfunc <span style="color: #339933;">*</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>

下面的程序捕捉两个用户自定义的信号进行处理:

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<span style="color: #339933;">#include &lt;signal .h&gt;</span>
<span style="color: #339933;">#include &lt;stdio .h&gt;</span>
<span style="color: #339933;">#include &lt;stdlib .h&gt;</span>

<span style="color: #993333;">typedef</span>    <span style="color: #993333;">void</span>    Sigfunc<span style="color: #009900;">(</span><span style="color: #993333;">int</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>
Sigfunc    <span style="color: #339933;">*</span>signal<span style="color: #009900;">(</span><span style="color: #993333;">int</span><span style="color: #339933;">,</span> Sigfunc <span style="color: #339933;">*</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>

<span style="color: #993333;">static</span> <span style="color: #993333;">void</span> sig_usr<span style="color: #009900;">(</span><span style="color: #993333;">int</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>

<span style="color: #993333;">int</span> main<span style="color: #009900;">(</span><span style="color: #993333;">int</span> argc<span style="color: #339933;">,</span><span style="color: #993333;">char</span> <span style="color: #339933;">**</span>argv<span style="color: #009900;">)</span>
<span style="color: #009900;">{</span>
<span style="color: #b1b100;">if</span><span style="color: #009900;">(</span>signal<span style="color: #009900;">(</span>SIGUSR1<span style="color: #339933;">,</span>sig_usr<span style="color: #009900;">)</span><span style="color: #339933;">==</span>SIG_ERR<span style="color: #009900;">)</span>
perror<span style="color: #009900;">(</span><span style="color: #ff0000;">"can't catch SIGUSR1"</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>
<span style="color: #b1b100;">if</span><span style="color: #009900;">(</span>signal<span style="color: #009900;">(</span>SIGUSR2<span style="color: #339933;">,</span>sig_usr<span style="color: #009900;">)</span><span style="color: #339933;">==</span>SIG_ERR<span style="color: #009900;">)</span>
perror<span style="color: #009900;">(</span><span style="color: #ff0000;">"can't catch SIGUSR2"</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>
<span style="color: #b1b100;">for</span><span style="color: #009900;">(</span><span style="color: #339933;">;;</span><span style="color: #009900;">)</span>
pause<span style="color: #009900;">(</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>
<span style="color: #009900;">}</span>

<span style="color: #993333;">static</span> <span style="color: #993333;">void</span> sig_usr<span style="color: #009900;">(</span><span style="color: #993333;">int</span> signo<span style="color: #009900;">)</span>
<span style="color: #009900;">{</span>
<span style="color: #b1b100;">if</span><span style="color: #009900;">(</span>signo<span style="color: #339933;">==</span>SIGUSR1<span style="color: #009900;">)</span>
<span style="color: #000066;">printf</span><span style="color: #009900;">(</span><span style="color: #ff0000;">"received SIGUSR1<span style="color: #000099; font-weight: bold;">n</span>"</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>
<span style="color: #b1b100;">else</span> <span style="color: #b1b100;">if</span><span style="color: #009900;">(</span>signo<span style="color: #339933;">==</span>SIGUSR2<span style="color: #009900;">)</span>
<span style="color: #000066;">printf</span><span style="color: #009900;">(</span><span style="color: #ff0000;">"received SIGUSR2<span style="color: #000099; font-weight: bold;">n</span>"</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>
<span style="color: #b1b100;">else</span>
<span style="color: #000066;">printf</span><span style="color: #009900;">(</span><span style="color: #ff0000;">"received signal %d <span style="color: #000099; font-weight: bold;">n</span>"</span><span style="color: #339933;">,</span>signo<span style="color: #009900;">)</span><span style="color: #339933;">;</span>
<span style="color: #009900;">}</span>

进行编译链接运行:

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$ <span style="color: #c20cb9; font-weight: bold;">cc</span> s.c
$ .<span style="color: #000000; font-weight: bold;">/</span>a.out <span style="color: #000000; font-weight: bold;">&amp;</span>                   #后台运行
<span style="color: #7a0874; font-weight: bold;">[</span><span style="color: #000000;">1</span><span style="color: #7a0874; font-weight: bold;">]</span> <span style="color: #000000;">4749</span>
$ <span style="color: #c20cb9; font-weight: bold;">kill</span> <span style="color: #660033;">-USR1</span> <span style="color: #000000;">4749</span>        #发送用户自定义信号
$ received SIGUSR1
$ <span style="color: #c20cb9; font-weight: bold;">kill</span> <span style="color: #660033;">-USR2</span> <span style="color: #000000;">4749</span>        #发送用户自定义信号
$ received SIGUSR2

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