signal example

 

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

void main() {
    sigset_t  _set;

    sigemptyset(&_set);
    sigaddset(&_set, SIGINT);
    sigaddset(&_set, SIGQUIT);

    if (sigismember(&_set, SIGINT) == 1) {
        printf("_set has signal SIGINT\n");
    } else {
        printf("has no signal\n");
    }

    if (sigismember(&_set, SIGQUIT) == 1) {
        printf("_set has signal SIGQUIT\n");
    } else {
        printf("has no signal\n");
    }

    sigdelset(&_set, SIGQUIT);

    if (sigismember(&_set, SIGQUIT) == 1) {
        printf("_set has signal SIGQUIT\n");
    } else {
        printf("has no signal\n");
    }
}

muhe221@muhe:~/test$ gcc -o sigset sigset.c
muhe221@muhe:~/test$ ./sigset
_set has signal SIGINT
_set has signal SIGQUIT
has no signal
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sleep(int)会被信号打断，它返回剩余时间

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

void handler(int signumber) {
   printf("\nreceive a signal: %d\n", signumber);
}

void main() {    

    struct sigaction act;
    memset(&act, 0, sizeof(act));
    sigemptyset(&act.sa_mask);
    act.sa_handler = &handler;
    sigaction(SIGINT, &act, NULL);

    int left = 100;
    printf("begin to while()\n");
    while (left > 0) {
       printf("begin to sleep(%d)\n", left);
       left = sleep(left);
       printf("sleep() finish\n");
    }
}

begin to while()
begin to sleep(100)
^C
receive a signal: 2
sleep() finish
begin to sleep(96)
^C
receive a signal: 2
sleep() finish
begin to sleep(89)
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