//實用工具程序之一，作用是允許用戶將消息轉發給程序或者程序不可用時反彈回信息

#include "fork.h"#include "strerr.h"#include "error.h"#include "wait.h"#include "sig.h"#include "exit.h"#define FATAL "bouncesaying: fatal: "void main(argc,argv)int argc;char **argv;{  int pid;  int wstat;  if (!argv[1])    strerr_die1x(100,"bouncesaying: usage: bouncesaying error [ program [ arg ... ] ]");  if (argv[2]) {    pid = fork();    if (pid == -1)      strerr_die2sys(111,FATAL,"unable to fork: ");    if (pid == 0) {      execvp(argv[2],argv + 2);      if (error_temp(errno)) _exit(111);      _exit(100);    }    if (wait_pid(&wstat,pid) == -1)      strerr_die2x(111,FATAL,"wait failed");    if (wait_crashed(wstat))      strerr_die2x(111,FATAL,"child crashed");    switch(wait_exitcode(wstat)) {      case 0: break;      case 111: strerr_die2x(111,FATAL,"temporary child error");      default: _exit(0);    }  }  strerr_die1x(100,argv[1]);}