1 #include "apue.h" 2  3 static void my_exit1(void); 4 static void my_exit2(void); 5  6  7 int main(void) 8 { 9     int ret = -1;10 11     ret = atexit(my_exit2);12     if(ret != 0)13         err_sys("can‘t not register my_exit2\r\n");14 15     ret = atexit(my_exit1);16     if(ret != 0)17         err_sys("can‘t not register my_exit1\r\n");18 19     ret = atexit(my_exit1);20     if(ret != 0)21         err_sys("can‘t not register my_exit1\r\n");22 23     printf("main done\r\n");24 25     exit(0);26 27 }28 29 static void my_exit1(void)30 {31     printf("first exit handler\r\n");32 }33 static void my_exit2(void)34 {35     printf("second exit handler\r\n");36 }