Question

我想知道是否有某种方法可以从孩子那里获取while语句（printf("Death of child: %d with exit code %d\n",i, WEXITSTATUS(status));）整数i的内部。

我正在从execlp获取输出（此程序内部有一个超时，该超时返回一个随机数），但是我想获取哪个是每个返回响应的标识i。 / p>

int main (int argc, char *argv[])
{
  int i;
  int pid;
  int status;
  int pro= atoi (argv[argc - 1]);
  char programName[] = "./child";

  if (argc < 2 || argc > 2){
    printf("Only one argument is allowed\n"); 
    exit (0);
  }


  for (i = 0; i < pro; i++)  
  { 
    pid = fork();
    if(pid == 0) 
    { 
      printf("Created child %d with pid=%d\n",i, getpid());
      char child[10];
      snprintf(child, 10, "%d", i);
      if (execlp(programName, programName, child, NULL) < 0){
        printf("Error running: %s\n",programName);
      }
      exit(2); 
    }    
  }
  while(wait(&status)>0)
  {
    if ( WIFEXITED(status) ){
      printf("Death of child: %d with timeout %d\n",i, WEXITSTATUS(status));
      if (WEXITSTATUS(status) > 5)
      {
        printf("Time exceeded\n");
      }
    }
  } 
  exit (0);
}

也许我的方法不正确。欢迎任何提示。我是c的新手。

Answer 1

wait将返回已更改过程的pid。要将其映射回i，请将从fork返回的所有pid保存到表中，并作为查找参考。

pid_t table[pro] = {0};
pid_t child=0;

for (i = 0; i < pro; i++)  
  { 
    pid = fork();
    if(pid == 0) 
    { 
      printf("Created child %d with pid=%d\n",i, getpid());
      char child[10];
      snprintf(child, 10, "%d", i);
      if (execlp(programName, programName, child, NULL) < 0){
        printf("Error running: %s\n",programName);
      }
      exit(2); 
    }
    else
    {
      table[i] = pid;
    }    
  }
  while((child=wait(&status)) > 0)
  {
    if ( WIFEXITED(status) ){

      i = -1;
      for (int j = 0; j < pro; j++)
      {
        if (table[j] == child))
        {
          i = j;
          break;
        }
      }

      printf("Death of child: %d with timeout %d\n",i, WEXITSTATUS(status));

从C的父进程获取子值（退出代码）

1 个答案: