（转载）Linux使用prctl API, 在父进程退出后，让子进程也退出

（转载）http://www.cnblogs.com/cornsea/archive/2010/06/08/1754369.html

例子1：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/prctl.h>

void my_system(void)
{
    pid_t pid;
    pid = fork();
    if (pid == 0)
    {
        //prctl(PR_SET_PDEATHSIG, SIGHUP);
        while (1)
        {
            printf("child running...\n");
            sleep(1);
        }
        exit(0);
    }
    else if (pid < 0)
    {
        printf("create failed\n");
    }
}

int main (int argc, char *argv[])
{
    int i = 0;
    my_system();

    while (i++ < 6)
    {
        printf("father running...\n");
        sleep(1);
    }

    printf("Main exit()\n");

    return 0;
}

程序输出：

[root@localhost ~]# ./a.out
child running...
father running...
child running...
father running...
child running...
father running...
child running...
father running...
child running...
father running...
child running...
father running...
child running...
Main exit()
[root@localhost ~]# child running...
child running...
child running...
child running...
child running...
child running...

可以看到当父进程结束了，子进程还在运行，此时的子进程变成了孤儿进程了。

例子2：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/prctl.h>

void my_system(void)
{
    pid_t pid;
    pid = fork();
    if (pid == 0)
    {
　　　　 // 设置当父进程退出时，子进程也退出
     prctl(PR_SET_PDEATHSIG, SIGHUP);
        while (1)
        {
            printf("child running...\n");
            sleep(1);
        }
        exit(0);
    }
    else if (pid < 0)
    {
        printf("create failed\n");
    }
}

int main (int argc, char *argv[])
{
    int i = 0;
    my_system();

    while (i++ < 6)
    {
        printf("father running...\n");
        sleep(1);
    }

    printf("Main exit()\n");

    return 0;
}

程序输出：

[root@localhost ~]# ./a.out
child running...
father running...
child running...
father running...
child running...
father running...
child running...
father running...
father running...
child running...
father running...
child running...
child running...
Main exit()
[root@localhost ~]#
[root@localhost ~]#
[root@localhost ~]#
从程序输出可以看到当父进程退出了，那么子进程也就退出了。