//http://blog.chinaunix.net/uid-24549279-id-71355.html

 /*

  ============================================================================

  Name        : test.c

  Author      : blank

  Version     :

  Copyright   : Your copyright notice

  Description : 程序清单8-3 8-4 演示不同的exit值

  ============================================================================

 */

 #include "ourhdr.h"

 #include <sys/wait.h>

 static void pr_exit(int status);

 int main(int argc, char *argv[])

 {

     pid_t    pid;

     int        status;

     if ((pid = fork()) < ){

         err_sys("fork error");

     }else if(pid == ){

         //child

         exit();

     }

     /*

      * wait for child and print its status

      */

     if (wait(&status) != pid){

         err_sys("wait error");

     }

     pr_exit(status);

     /*

      * child generates SIGABRT

      */

     if ((pid = fork()) < ){

         err_sys("fork_error");

     }else if (pid == ){

         abort();

     }

     /*

      * wait for child and print its status

      */

     if (wait(&status) != pid){

         err_sys("wait error");

     }

     pr_exit(status);

     if ((pid = fork()) < ){

         err_sys("fork error");

     }else if(pid == ){

         // child divide by 0 generates SIGFPE

         status/=;

     }

     /*

      * wait for child and print its status

      */

     if (wait(&status) != pid){

         err_sys("wait error");

     }

     pr_exit(status);

 }

 static void pr_exit(int status)

 {

     if (WIFEXITED(status)){

         printf("normal termination, exit status = %d\n", WEXITSTATUS(status));

     }else if (WIFSIGNALED(status)){

         printf("abnormal termination, signal number=%d%s\n", WTERMSIG(status),

 #ifdef WCOREDUMP

         WCOREDUMP(status) ? " (core file generated )" : "");

 #else

         "");

 #endif

     }else if(WIFSTOPPED(status)){

             printf("child stopped, signal number=%d\n", WSTOPSIG(status));

         }

 }