1	/** sig.c    --- demo how to catch/handle the system signal in C program
     2	 ** by Wen-Nung Tsai.  ** @CopyLeft reserved
     3	 *** gcc sig.c
     4	 *** ./a.out
     5	****** from "man signal":
     6	                 SYNOPSIS
     7	                      #include <signal.h>
     8	                      void (*signal(int sig, void(*func)(int))()
     9	*** In signal(), it will call func in this way:
    10	                 (*func)(sig);
    11	**********************/
    12	extern long time(); /* in <sys/time.h> */
    13	#include <signal.h>
    14	#include <setjmp.h>
    15	#include <stdio.h>
    16	void myisr1(int);  /* an ISR to handle some interrupts */
    17	void myisr2(int tni){printf("he he he!\n");};  /* for other signals */
    18	long k=0, status=0, *p;
    19	jmp_buf env;  /* for use in setjmp(), longjmp() */
    20	int main()
    21	{  /*** tell the system we want to catch some signals ***/
    22	     signal(SIGINT, (void (*)(int)) myisr1 );   /* See K&R Appendix B9 */
    23	     signal(SIGSEGV, *myisr1 ); /* signal(SIGSEGV, (void (*)(int)) myisr1 );*/
    24	     printf("\nWelcome to Disney Land...\n");
    25	     srand(time(0));  /* use current time to set seed of rand() */
    26	     if(rand()%100 < 50){
    27		if(setjmp(env)==0)     /* See K&R Appendix B8 */
    28		   *p=38;      /* 這本來應會segmentation fault而引起 core dump ! */
    29	        else goto eoj;     /* 後面的longjmp() 會跑回此處 else ! */
    30	     }
    31	     printf("Here we go!\n");
    32	  loop_a_while:
    33	     while(k<12345){
    34	        printf("%ld ",k++);
    35	     }
    36	     printf("\n=== bye bye ===\n");  return 0;
    37	  eoj:
    38	     system("echo -n Now:"); system("date");
    39	     printf("\n=== abnormal stop:-(\n");  return 1;
    40	}
    41	void myisr1(int x) /* Interrupt Service Routine */
    42	{
    43	   fflush(stdout);  /* try to flush current buffer */
    44	   switch(x){
    45	     case SIGINT:
    46	       printf("\nHey, [sig no=%d] Do NOT hit Control_C\n", x);
    47	       k=12340;
    48	       break;   /* don't forget to take a break :-) */
    49	     default:
    50	       printf("Outch! Seems Segmentation Falt or Fatal error\n");
    51	       status = 49;
    52	       longjmp(env, 123);  /* return a non-zero value */
    53	   } /*switch case*/       /* longjmp() will goto recent if(setjmp... */
    54	   return;
    55	}
/*** 說明執行這程式會怎樣以及結束前敲Control_C會如何?
 (hint: 多試幾次! 
        用到的函數都可在 K&R 的附錄B 中找到, 中英文皆同)
 (以後如果你的工作是寫程式, 這程式對你非常有用! 信不信由你:-)
******/
From: jwlin@csie.nctu.edu.tw (蔚藍~~~~)
      試了幾次..........有兩種情況..............
        第一種就是一直印數字，在印到 12344時會結束.....印出掰掰.....
              假如按 ctrl-c 會出現Hey, [sig no=2] Do NOT hit Control_C
              然後又印一些, 但一定印到 12344 程式結束，印出掰掰.........
        第二種就是直接Segmentation Falt or Fatal error
              印出=== abnormal stop:-(
                就結束了........
1 2 ...
7438 7439 7440 7441 7442 7443 7444 7445 7446 7447 7448 7449 7450 7451 7^C
Hey, [sig no=2] Do NOT hit Control_C
7915 7916 7917 7918 12340 12341 12342 12343 12344
=== bye bye ===

Welcome to Disney Land...
Outch! Seems Segmentation Falt or Fatal error
Now:Wed May 15 20:44:42 CST 1996

=== abnormal stop:-(