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;

    while(1){

        sigwait(&set,&signum);

        if(SIGUSR1 == signum)

        myfunc();

        if(SIGUSR2 == signum)

        {

            printf("I will sleep 2 second and exit\n");

            sleep(2);

            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);

    while(1)

    {

        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; 

    } 



return 0;

}















#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) { 

case 1: 

printf("Get a signal -- SIGHUP "); 

break; 

case 2: 

printf("Get a signal -- SIGINT "); 

break; 

case 3: 

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 = 5; 

    

    printf("process id is %d ",getpid()); 

    signal(SIGALRM, sigroutine); 

    signal(SIGVTALRM, sigroutine); 

    

    value.it_value.tv_sec = 1; 

    value.it_value.tv_usec = 0; 

    value.it_interval.tv_sec = 1; 

    value.it_interval.tv_usec = 0; 

    setitimer(ITIMER_REAL, &value, &ovalue); 

    

    value2.it_value.tv_sec = 0; 

    value2.it_value.tv_usec = 500000; 

    value2.it_interval.tv_sec = 0; 

    value2.it_interval.tv_usec = 500000; 

    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("a = %d\n",a);  //0

 printf("b = %d\n",b);  //1



 return 0;

}