前言

在Linux环境下࿰c;信号是一种重要的进程间通信机制࿰c;用于处理异步事件和控制进程行为。除了使用signal函数来设置信号处理函数外࿰c;还有一些其他的信号相关函数࿰c;如kill、raise、pause和alarm࿰c;它们提供了更多的信号处理和管理功能。本文将介绍这些函数的基本概念和用法࿰c;帮助读者更好地理解信号处理在Linux编程中的应用。

一、函数介绍

1.1 kill() 函数

• 原型： <code>int kill(pid_t pid, int sig);code>
• 作用： 用于向指定的进程发送信号。
• 参数：
  • <code>pidcode>：要发送信号的进程的 ID。
  • <code>sigcode>：要发送的信号的编号。
• 返回值： 如果成功࿰c;则返回0；如果失败࿰c;则返回-1。
• 示例代码：

  <code class="prism language-c">class="token macro property">class="token directive-hash">#class="token directive keyword">include class="token string"><stdio.h>
  class="token macro property">class="token directive-hash">#class="token directive keyword">include class="token string"><signal.h>
  class="token macro property">class="token directive-hash">#class="token directive keyword">include class="token string"><unistd.h>class="token keyword">int class="token function">mainclass="token punctuation">(class="token punctuation">) class="token punctuation">{class="token class-name">pid_t pid class="token operator">= class="token function">getpidclass="token punctuation">(class="token punctuation">)class="token punctuation">; class="token comment">// 获取当前进程的 IDclass="token keyword">int result class="token operator">= class="token function">killclass="token punctuation">(pidclass="token punctuation">, SIGKILLclass="token punctuation">)class="token punctuation">; class="token comment">// 发送 SIGKILL 信号给当前进程class="token keyword">if class="token punctuation">(result class="token operator">== class="token number">0class="token punctuation">) class="token punctuation">{class="token function">printfclass="token punctuation">(class="token string">"Signal sent successfully.\n"class="token punctuation">)class="token punctuation">;class="token punctuation">} class="token keyword">else class="token punctuation">{class="token function">printfclass="token punctuation">(class="token string">"Failed to send signal.\n"class="token punctuation">)class="token punctuation">;class="token punctuation">}class="token keyword">return class="token number">0class="token punctuation">;
  class="token punctuation">}
  code>

c="https://img-blog.csdnimg.cn/direct/1d6ee2fc348c427481a1f93d8baaf007.png#pic_center" alt="在这里插入图片描述" />

1.2 raise() 函数

• 原型： <code>int raise(int sig);code>
• 作用： 用于向当前进程发送信号。
• 参数：
  • <code>sigcode>：要发送的信号的编号。
• 返回值： 如果成功࿰c;则返回0；如果失败࿰c;则返回非0。
• 示例代码：

  <code class="prism language-c">class="token macro property">class="token directive-hash">#class="token directive keyword">include class="token string"><stdio.h>
  class="token macro property">class="token directive-hash">#class="token directive keyword">include class="token string"><signal.h>class="token keyword">int class="token function">mainclass="token punctuation">(class="token punctuation">) class="token punctuation">{class="token keyword">int result class="token operator">= class="token function">raiseclass="token punctuation">(SIGINTclass="token punctuation">)class="token punctuation">; class="token comment">// 发送 SIGINT 信号给当前进程class="token keyword">if class="token punctuation">(result class="token operator">== class="token number">0class="token punctuation">) class="token punctuation">{class="token function">printfclass="token punctuation">(class="token string">"Signal sent successfully.\n"class="token punctuation">)class="token punctuation">;class="token punctuation">} class="token keyword">else class="token punctuation">{class="token function">printfclass="token punctuation">(class="token string">"Failed to send signal.\n"class="token punctuation">)class="token punctuation">;class="token punctuation">}class="token keyword">return class="token number">0class="token punctuation">;
  class="token punctuation">}
  code>

c="https://img-blog.csdnimg.cn/direct/479dd4cdcc48472ca9ec88827b3496d0.png#pic_center" alt="在这里插入图片描述" />

1.3 pause() 函数

• 原型： <code>int pause(void);code>
• 作用： 让进程挂起࿰c;直到收到一个信号。
• 参数： 无参数。
• 返回值： 被信号中断时返回-1࿰c;否则不返回。
• 示例代码：

  <code class="prism language-c">class="token macro property">class="token directive-hash">#class="token directive keyword">include class="token string"><stdio.h>
  class="token macro property">class="token directive-hash">#class="token directive keyword">include class="token string"><signal.h>class="token keyword">void class="token function">handlerclass="token punctuation">(class="token keyword">int sigclass="token punctuation">) class="token punctuation">{class="token function">printfclass="token punctuation">(class="token string">"Signal received.\n"class="token punctuation">)class="token punctuation">;
  class="token punctuation">}class="token keyword">int class="token function">mainclass="token punctuation">(class="token punctuation">) class="token punctuation">{class="token function">signalclass="token punctuation">(SIGINTclass="token punctuation">, handlerclass="token punctuation">)class="token punctuation">; class="token comment">// 设置信号处理函数class="token function">printfclass="token punctuation">(class="token string">"Waiting for signal...\n"class="token punctuation">)class="token punctuation">;class="token function">pauseclass="token punctuation">(class="token punctuation">)class="token punctuation">; class="token comment">// 挂起进程直到收到信号class="token function">printfclass="token punctuation">(class="token string">"Resuming after pause.\n"class="token punctuation">)class="token punctuation">;class="token keyword">return class="token number">0class="token punctuation">;
  class="token punctuation">}
  code>

c="https://img-blog.csdnimg.cn/direct/31dde7bafba44963a1fc46115660bacb.png#pic_center" alt="在这里插入图片描述" />

1.4 alarm() 函数

• 原型： <code>unsigned int alarm(unsigned int seconds);code>
• 作用： 设置一个定时器࿰c;在指定的秒数后发送 SIGALRM 信号给当前进程。
• 参数：
  • <code>secondscode>：定时器的时长࿰c;以秒为单位。
• 返回值： 返回上一个定时器剩余的秒数࿰c;如果之前没有定时器࿰c;则返回0。
• 示例代码：

  <code class="prism language-c">class="token macro property">class="token directive-hash">#class="token directive keyword">include class="token string"><stdio.h>
  class="token macro property">class="token directive-hash">#class="token directive keyword">include class="token string"><unistd.h>
  class="token macro property">class="token directive-hash">#class="token directive keyword">include class="token string"><signal.h>class="token keyword">void class="token function">handlerclass="token punctuation">(class="token keyword">int sigclass="token punctuation">) class="token punctuation">{class="token function">printfclass="token punctuation">(class="token string">"Alarm triggered.\n"class="token punctuation">)class="token punctuation">;
  class="token punctuation">}class="token keyword">int class="token function">mainclass="token punctuation">(class="token punctuation">) class="token punctuation">{class="token function">signalclass="token punctuation">(SIGALRMclass="token punctuation">, handlerclass="token punctuation">)class="token punctuation">; class="token comment">// 设置信号处理函数class="token keyword">unsigned class="token keyword">int remaining class="token operator">= class="token function">alarmclass="token punctuation">(class="token number">5class="token punctuation">)class="token punctuation">; class="token comment">// 设置定时器为5秒࿰c;并获取之前的剩余时间class="token function">printfclass="token punctuation">(class="token string">"Waiting for alarm...\n"class="token punctuation">)class="token punctuation">;class="token function">sleepclass="token punctuation">(class="token number">10class="token punctuation">)class="token punctuation">; class="token comment">// 睡眠10秒࿰c;等待触发定时器class="token function">printfclass="token punctuation">(class="token string">"Resuming after alarm.\n"class="token punctuation">)class="token punctuation">;class="token keyword">return class="token number">0class="token punctuation">;
  class="token punctuation">}
  code>

c="https://img-blog.csdnimg.cn/direct/9e7e3d75f7d04f98948a9e8186bcb38d.png#pic_center" alt="在这里插入图片描述" />

总结

通过学习kill、raise、pause和alarm等信号相关函数࿰c;我们扩展了对信号处理和管理的认识。这些函数可以让我们更灵活地控制信号的发送、处理和等待࿰c;从而实现更复杂的信号交互和进程控制逻辑。然而࿰c;在使用这些函数时࿰c;需要注意理解它们的功能和用法࿰c;以避免不必要的错误和问题。综上所述࿰c;信号相关函数是Linux编程中不可或缺的重要工具࿰c;熟练掌握它们将有助于编写更加健壮和高效的程序。