测试signal.h

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

void handler(int sig);
void raise_sig(void);

int main()
{
    void (*orig_handler)(int);

    printf("Install handler for signal:%d\n",SIGINT);
    orig_handler=signal(SIGINT,handler);
    raise_sig();

    printf("Changing handler to SIG_IGN\n");
    signal(SIGINT,SIG_IGN);
    raise_sig();

    printf("Restoring original handler\n");
    signal(SIGINT,orig_handler);
           raise_sig();

    printf("Program terminates normally\n");
    return 0;
}

void handler(int sig)
{
    printf("Handler called for signal %d\n",sig);
}

void raise_sig(void)
{
    raise(SIGINT);
}