黑马《linux系统编程》学习笔记（从51到55）

五十一. kill函数的使用

这里我们写一个kill.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 


int main(int argc, const char* argv[])
{
    pid_t pid = fork();
    if(pid == -1)
    {
        perror("fork error");
        exit(1);
    }

    if(pid > 0)
    {
        while(1)
        {
            printf("parent process pid = %d\n", getpid());
            sleep(1);
        }
    }
    else if(pid == 0)
    {
        sleep(2);
        // 弑父
        kill(getppid(), SIGKILL);
    }

    return 0;
}

运行一下

[root@VM_0_15_centos 7Day]# ls
alarm.c        homework  raise.c      sigaction.c  signal.c
alarm_uncle.c  kill.c    setitimer.c  sigmaks.c    thread_attr.c
[root@VM_0_15_centos 7Day]# gcc kill.c
[root@VM_0_15_centos 7Day]# ./a.out
parent process pid = 30669
parent process pid = 30669
parent process pid = 30669
Killed

五十二. kill函数pid参数介绍

 

 五十三. raise和abort函数

写一个raise.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 


int main(int argc, const char* argv[])
{
    pid_t pid = fork();

    if(pid > 0)
    {
        // parent
        int s;
                pid_t wpid =  wait(&s);
                printf("child died pid = %d\n",wpid);

        if(WIFSIGNALED(s))
        {
            printf("term by signal: %d\n", WTERMSIG(s));
        }
    }
    else if(pid == 0)
    {
        raise(SIGINT);
       // abort();
    }

    return 0;
}

运行一下：

[root@VM_0_15_centos 7Day]# vim raise.c
[root@VM_0_15_centos 7Day]# ls
alarm.c        a.out     kill.c   setitimer.c  sigmaks.c  thread_attr.c
alarm_uncle.c  homework  raise.c  sigaction.c  signal.c
[root@VM_0_15_centos 7Day]# gcc raise.c
[root@VM_0_15_centos 7Day]# ./a.out
child died pid = 12026
term by signal: 2

写一个abort.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 


int main(int argc, const char* argv[])
{
    pid_t pid = fork();

    if(pid > 0)
    {
        // parent
        int s;
                pid_t wpid =  wait(&s);
                printf("child died pid = %d\n",wpid);

        if(WIFSIGNALED(s))
        {
            printf("term by signal: %d\n", WTERMSIG(s));
        }
    }
    else if(pid == 0)
    {
       // raise(SIGINT);
        abort();
    }

    return 0;
}

运行一下

[root@VM_0_15_centos 7Day]# ls
abort.c  alarm_uncle.c  kill.c   setitimer.c  sigmaks.c  thread_attr.c
alarm.c  homework       raise.c  sigaction.c  signal.c
[root@VM_0_15_centos 7Day]# gcc abort.c
[root@VM_0_15_centos 7Day]# ./a.out
child died pid = 12434
term by signal: 6

五十四. alarm函数

alarm的文档

写一个alarm.c

#include 
#include 
#include 
#include 
#include 
#include 


int main(int argc, const char* argv[])
{
    int ret = alarm(5);
    printf("ret = %d\n", ret);

    sleep(2);

    ret = alarm(2);
    printf("ret = %d\n", ret);

    while(1)
    {
        printf("hello\n");
        sleep(1);
    }

    return 0;
}

运行结果

[root@VM_0_15_centos 7Day]# gcc alarm.c
[root@VM_0_15_centos 7Day]# ./a.out
ret = 0
ret = 3
hello
hello
Alarm clock

五十五. 计算1s数多少个数