#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <fcntl.h>#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <signal.h>#define ERR_EXIT(m) \do \{ \perror(m); \exit(EXIT_FAILURE); \} while(0)void handler(int sig);int main(int argc, char *argv[])
{struct sigaction act;//安装信号时需要传参act.sa_handler = handler;sigemptyset(&act.sa_mask);//先将sa_mask清空，关于这个属性的用法之后实验再说明act.sa_flags = 0;//同样将sa_flags设为0，这个实现不需要关心，之后会说明if (sigaction(SIGINT, &act, NULL) < 0)//安装信号ERR_EXIT("sigaction error\n");for (;;)pause();return 0;
}void handler(int sig)
{printf("recv a sig=%d\n", sig);
}

#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <fcntl.h>#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <signal.h>#define ERR_EXIT(m) \do \{ \perror(m); \exit(EXIT_FAILURE); \} while(0)void handler(int sig);
__sighandler_t my_signal(int sig, __sighandler_t handler);//这跟signal的信号安装函数声明一样，实现自己的signalint main(int argc, char *argv[])
{
/*struct sigaction act;act.sa_handler = handler;sigemptyset(&act.sa_mask);act.sa_flags = 0;if (sigaction(SIGINT, &act, NULL) < 0)ERR_EXIT("sigaction error\n");
*/my_signal(SIGINT, handler);for (;;)pause();return 0;
}__sighandler_t my_signal(int sig, __sighandler_t handler)
{struct sigaction act;struct sigaction oldact;//保存最初的行为act.sa_handler = handler;sigemptyset(&act.sa_mask);act.sa_flags = 0;if (sigaction(sig, &act, &oldact) < 0)return SIG_ERR;return oldact.sa_handler;
}void handler(int sig)
{printf("recv a sig=%d\n", sig);
}

#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <fcntl.h>#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <signal.h>#define ERR_EXIT(m) \do \{ \perror(m); \exit(EXIT_FAILURE); \} while(0)void handler(int sig);int main(int argc, char *argv[])
{struct sigaction act;act.sa_handler = handler;sigemptyset(&act.sa_mask);act.sa_flags = 0;if (sigaction(SIGINT, &act, NULL) < 0)ERR_EXIT("sigaction error");for (;;)pause();return 0;
}void handler(int sig)
{printf("recv a sig=%d\n", sig);sleep(5);//故意睡眠5秒是为了看在执行期间按了ctrl+\就能立马响应退出信号
}

#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <fcntl.h>#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <signal.h>#define ERR_EXIT(m) \do \{ \perror(m); \exit(EXIT_FAILURE); \} while(0)void handler(int sig);int main(int argc, char *argv[])
{struct sigaction act;act.sa_handler = handler;sigemptyset(&act.sa_mask);//sigaddset(&act.sa_mask, SIGQUIT);//将其sa_mask注册去掉，也就是清零了act.sa_flags = 0;sigset_t s;sigemptyset(&s);sigaddset(&s, SIGINT);sigprocmask(SIG_BLOCK, &s, NULL);//这就是之前学的，将SIGINT加入到进程的屏蔽字中if (sigaction(SIGINT, &act, NULL) < 0)ERR_EXIT("sigaction error");for (;;)pause();return 0;
}void handler(int sig)
{printf("recv a sig=%d\n", sig);sleep(5);
}