signal

//signaltest.c
// 子线程阻塞，等待信号，然后输出字符串
// 主线程从键盘录入字符，给子线程发信号。
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <pthread.h>
#include <time.h>
pthread_t tid;
sigset_t set;
void myfunc()
{
    printf("hello\n");
}

static void* mythread(void *p)
{
    int signum;
    ){
        sigwait(&set,&signum);
        if(SIGUSR1 == signum)
        myfunc();
        if(SIGUSR2 == signum)
        {
            printf("I will sleep 2 second and exit\n");
            sleep();
            break;
        }
    }
}

int main()
{
    char tmp;
    void* status;
    sigemptyset(&set);
    sigaddset(&set,SIGUSR1);
    sigaddset(&set,SIGUSR2);
    sigprocmask(SIG_SETMASK,&set,NULL);

    pthread_create(&tid,NULL,mythread,NULL);
    )
    {
        printf(":");
        scanf("%c",&tmp);
        if('a' == tmp)
        {
            pthread_kill(tid,SIGUSR1); //发送SIGUSR1，打印字符串。
        }
        else if('q'==tmp)
        {
            pthread_kill(tid,SIGUSR2); //发出SIGUSR2信号，让线程退出，如果发送SIGKILL，线程将直接退出。
            pthread_join(tid,&status); //等待线程tid执行完毕，这里阻塞。
            printf("finish\n");
            break;
        }
        else
            continue;
    } 

;
}

#include <signal.h>
#include <unistd.h>
#include <stdio.h>
void sigroutine(int dunno) { /* 信号处理例程，其中dunno将会得到信号的值 */
switch (dunno) {
:
printf("Get a signal -- SIGHUP ");
break;
:
printf("Get a signal -- SIGINT ");
break;
:
printf("Get a signal -- SIGQUIT ");
break;
}
return;
} 

int main() {
printf("process id is %d ",getpid());
signal(SIGHUP, sigroutine); //* 下面设置三个信号的处理方法
signal(SIGINT, sigroutine);
signal(SIGQUIT, sigroutine);
for (;;) ;
} 

#include <signal.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/time.h>
int sec; 

void sigroutine(int signo) {
    switch (signo) {
        case SIGALRM:
            printf("Catch a signal -- SIGALRM ");
            break;
        case SIGVTALRM:
            printf("Catch a signal -- SIGVTALRM ");
            break;
    }
    return;
} 

int main() {
    struct itimerval value,ovalue,value2;
    sec = ; 

    printf("process id is %d ",getpid());
    signal(SIGALRM, sigroutine);
    signal(SIGVTALRM, sigroutine); 

    value.it_value.tv_sec = ;
    value.it_value.tv_usec = ;
    value.it_interval.tv_sec = ;
    value.it_interval.tv_usec = ;
    setitimer(ITIMER_REAL, &value, &ovalue); 

    value2.it_value.tv_sec = ;
    value2.it_value.tv_usec = ;
    value2.it_interval.tv_sec = ;
    value2.it_interval.tv_usec = ;
    setitimer(ITIMER_VIRTUAL, &value2, &ovalue); 

    for (;;) ;
} 

#include <stdio.h>
#define SIG_DFL ((void(*)(int))0)
#define SIG_IGN ((void(*)(int))1)

int main()
{
 int a = (int)SIG_DFL;
 int b = (int)SIG_IGN;

 printf(
 printf(

 ;
}