C3.js连接失败(C3.js connection fails)

 你没有在孩子中调用剪切，文件描述符也搞乱了。 
 
 要执行任务，您必须关闭父项的stdout，并在execvp之前在父项中执行write end stdout。 在孩子中你必须关闭孩子的 stdin并在execvp之前将你的孩子的阅读结束作为stdin。 通过这种方式， your parent's stdout is stdin of your child （创建管道b / w两个）。 
 
int main()
{
   int filedes[2];
   int p;
   pid_t pid = 0, pid1 = 0;
   p=pipe(filedes);
   FILE *stream;
   char buff[20];
   char *args[80];

   printf("pipe command returns %d, %d ,%d\n",p, filedes[0],filedes[1]);

   if(pipe(filedes) == -1) /* Create the pipe */
      printf("error pipe");
      pid1=fork();
      pid=getpid();
      switch (pid1) { /* Create a child process */
      case -1:
         printf("error fork"); break;
      case 0: /* Child */
      /* Close unused write end */
      /* Child can now read from pipe */
         if (close(filedes[1]) == -1)
            printf("error close");
         printf("I am a child process pid %d, and will read from pipe\n",pid);

         close(0); //close stdin of child
         dup(filedes[0]); //make pipes read end stdin of child

         args[0] = "cut";
         args[1] = "-b";
         args[2] = "1";
         args[3] = NULL;
         execvp(args[0],args);
         break;

         default: /* Parent */
         /* Close unused read end */
         /* Parent can now write to pipe */
         if (close(filedes[0]) == -1)
            printf("error close");
         printf("I am the parent process pid %d, and will write to pipe\n", pid );

         close(1); //close stdout
         dup(filedes[1]); //make write end of pipe stdout of parent
         args[0] = "ls";
         args[1] = "-l";
         args[2] = NULL;
         execvp(args[0],args);
         break;
   }
}

You didn't called the cut in the child and also the file descriptors are messed up here.
 
For performing the task you have to close the stdout of parent and make the write end stdout in parent before execvp. In child you have to close stdin of child and make read end as stdin to your child before execvp. In that way your parent's stdout is stdin of your child(creating the pipe b/w two).
 
int main()
{
   int filedes[2];
   int p;
   pid_t pid = 0, pid1 = 0;
   p=pipe(filedes);
   FILE *stream;
   char buff[20];
   char *args[80];

   printf("pipe command returns %d, %d ,%d\n",p, filedes[0],filedes[1]);

   if(pipe(filedes) == -1) /* Create the pipe */
      printf("error pipe");
      pid1=fork();
      pid=getpid();
      switch (pid1) { /* Create a child process */
      case -1:
         printf("error fork"); break;
      case 0: /* Child */
      /* Close unused write end */
      /* Child can now read from pipe */
         if (close(filedes[1]) == -1)
            printf("error close");
         printf("I am a child process pid %d, and will read from pipe\n",pid);

         close(0); //close stdin of child
         dup(filedes[0]); //make pipes read end stdin of child

         args[0] = "cut";
         args[1] = "-b";
         args[2] = "1";
         args[3] = NULL;
         execvp(args[0],args);
         break;

         default: /* Parent */
         /* Close unused read end */
         /* Parent can now write to pipe */
         if (close(filedes[0]) == -1)
            printf("error close");
         printf("I am the parent process pid %d, and will write to pipe\n", pid );

         close(1); //close stdout
         dup(filedes[1]); //make write end of pipe stdout of parent
         args[0] = "ls";
         args[1] = "-l";
         args[2] = NULL;
         execvp(args[0],args);
         break;
   }
}