Linux_信号操作demo

main1.c

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
    while(1) {
        printf("work...
");
        sleep(3);
    }

    return 0;
}

main2.c

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>


void myhandle(int sig) 
{
    printf("Catch a signal : %d
", sig);
}

int main(void) 
{

    signal(SIGINT, myhandle);
    while (1) {

    }

    return 0;
}

main3.c

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>

void myhandle(int sig) 
{
    static int cnt = 0;
    printf("Catch a signal : %d
", sig);

    signal(SIGINT, SIG_DFL); //µ»Õ¨”⁄signal(sig, SIG_DFL);
}

int main(void) 
{
    signal(SIGINT, myhandle);

    while (1) {

    }

    return 0;
}

main4.c

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>

void myhandle(int sig) 
{
    printf("Catch a signal : %d
", sig);
}

int main(void) 
{
    struct sigaction act;

    act.sa_handler = myhandle;
    sigemptyset(&act.sa_mask);
       act.sa_flags = 0;

    sigaction(SIGINT, &act, 0);

    while (1) {

    }

    return 0;
}

main5.c

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>

void myhandle(int sig) 
{
    printf("Catch a signal : %d
", sig);
}

int main(void) 
{
    struct sigaction act;

    act.sa_handler = myhandle;
    sigemptyset(&act.sa_mask);
    //act.sa_flags = 0;
    act.sa_flags = SA_RESETHAND;

    sigaction(SIGINT, &act, 0);

    while (1) {

    }

    return 0;
}

main6.c

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>

int workflag = 0;

void work_up_handle(int sig) 
{
    workflag = 1;
}

void work_down_handle(int sig) 
{
    workflag = 0;
}



int main(void) 
{
    pid_t pd;
    char c;


    pd = fork();
    if (pd == -1) {
        printf("fork error!
");
        exit(1);
    } else if (pd == 0) {
        char *msg;
        struct sigaction act; 
        act.sa_flags = 0;
        act.sa_handler = work_up_handle;
        sigemptyset(&act.sa_mask);      
        sigaction(SIGUSR1, &act, 0);

        act.sa_handler = work_down_handle;
        sigaction(SIGUSR2, &act, 0);

        while (1) {
            if (!workflag) {
                msg = "child process work!";
            } else {
                msg = "CHILD PROCESS WORK!";
            }
            printf("%s
", msg);
            sleep(1);
        }

    } else {
        while(1) {
            c = getchar();
            if (c == 'A') {
                kill(pd, SIGUSR1);
            } else if (c == 'a') {
                kill(pd, SIGUSR2);
            }
        }
    }


    return 0;
}

main7.c

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>

int wakeflag = 0;

void wake_handle(int sig) 
{
    wakeflag = 1;
}

int main(void) 
{
    pid_t pd;
    char c;


    pd = fork();
    if (pd == -1) {
        printf("fork error!
");
        exit(1);
    } else if (pd == 0) {
        sleep(5);
        kill(getppid(), SIGALRM);
    } else {
        struct sigaction act; 
        act.sa_handler = wake_handle;
        act.sa_flags = 0;
        sigemptyset(&act.sa_mask);

        sigaction(SIGALRM,  &act, 0);

        pause(); //∞—∏√Ω¯≥Ãπ“∆£¨÷±µΩ ’µΩ»Œ“‚“ª∏ˆ–≈∫≈

        if (wakeflag) {
            printf("Alarm clock work!!!
");
        }
    }

    return 0;
}

main8.c

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <time.h>

int wakeflag = 0;

void wake_handle(int sig) 
{
    wakeflag = 1;
}

int main(void) 
{
    int ret;

    struct sigaction act;
    act.sa_flags = 0;
    act.sa_handler = wake_handle;
    sigemptyset(&act.sa_mask);
    sigaction(SIGALRM, &act, 0);

    printf("time =%ld
", time((time_t*)0));

    ret = alarm(5);
    if (ret == -1) {
        printf("alarm error!
");
        exit(1);
    }

    //π“∆µ±«∞Ω¯≥ã¨÷±µΩ ’µΩ»Œ“‚“ª∏ˆ–≈∫≈
    pause();

    if (wakeflag) {
        printf("wake up, time =%ld
", time((time_t*)0));
    }

    return 0;
}

main9.c

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>

int wakeflag = 0;

void wake_handle(int sig) 
{
    printf("in handle
");   // ‘⁄∏√–≈∫≈¥¶¿Ì∫Ø ˝÷– π”√printf£¨“‘±„µ˜ ‘£¨±æ≤ª“À π”√£¨“ÚŒ™printf «≤ªø…÷ÿ»Îµƒ
    sleep(10);
    printf("in handle2
");
    wakeflag = 1;
}

int main(void) 
{
    pid_t pd;
    char c;

    pd = fork();
    if (pd == -1) {
        printf("fork error!
");
        exit(1);
    } else if (pd == 0) {
        sleep(3);
        kill(getppid(), SIGALRM);
    } else {
        struct sigaction act; 
        act.sa_handler = wake_handle;
        act.sa_flags = 0;
        sigemptyset(&act.sa_mask);

        sigaddset(&act.sa_mask, SIGALRM); //SIGINT);

        sigaction(SIGALRM,  &act, 0);

        pause(); //∞—∏√Ω¯≥Ãπ“∆£¨÷±µΩ ’µΩ»Œ“‚“ª∏ˆ–≈∫≈


        if (wakeflag) {
            printf("Alarm clock work!!!
");
        } else {
            printf("Alarm clock not work!
");
        }
    }

    return 0;
}