NAME
       raise - send a signal to the caller

SYNOPSIS
       #include <signal.h>

       int raise(int sig);

DESCRIPTION
       The  raise()  function  sends  a signal to the calling process or thread.  In a
       single-threaded program it is equivalent to

           kill(getpid(), sig)
 
;

       In a multithreaded program it is equivalent to

           pthread_kill(pthread_self(), sig);

       If the signal causes a handler to be called, raise() will return only after the
       signal handler has returned.

使用kill()呼叫

/*************************************************************************\
*                  Copyright (C) Michael Kerrisk, 2018.                   *
*                                                                         *
* This program is free software. You may use, modify, and redistribute it *
* under the terms of the GNU General Public License as published by the   *
* Free Software Foundation, either version 3 or (at your option) any      *
* later version. This program is distributed without any warranty.  See   *
* the file COPYING.gpl-v3 for details.                                    *
\*************************************************************************/
 


/* Listing 20-3 */

/* t_kill.c

   Send a signal using kill(2) and analyze the return status of the call.
*/
#include <signal.h>
#include "tlpi_hdr.h"

int
main(int argc, char *argv[])
{
    int s, sig;

    if (argc != 3 || strcmp(argv[1], "--help") == 0)
        usageErr("%s pid sig-num\n", argv[
 
0]);

    sig = getInt(argv[2], 0, "sig-num");

    s = kill(getLong(argv[1], 0, "pid"), sig);

    if (sig != 0) {
        if (s == -1)
            errExit("kill");

    } else {                    /* Null signal: process existence check */
        if (s == 0) {
            printf("Process exists and we can send it a signal\n");
        } else {
            if (errno == EPERM)
                printf("Process exists, but we don't have "
                       "permission to send it a signal\n");
            else if (errno == ESRCH)
                printf("Process does not exist\n");
            else
                errExit("kill");
        }
    }

    exit(EXIT_SUCCESS);
}

```\

![在這裡插入圖片描述](https://img-blog.csdnimg.cn/20181125192902784.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2FuZHJld2dpdGh1Yg==,size_16,color_FFFFFF,t_70)

顯示訊號描述
![在這裡插入圖片描述](https://img-blog.csdnimg.cn/20181125193140572.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2FuZHJld2dpdGh1Yg==,size_16,color_FFFFFF,t_70)