#include <sys/wait.h>
       #include <assert.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <unistd.h>
       #include <string.h>
 
       int
       main(int argc, char *argv[])
       {
           int pfd[2];
           pid_t cpid;
           char buf;
 
           assert(argc == 2);
 
           if (pipe(pfd) == -1) { perror("pipe"); exit(EXIT_FAILURE); }
 
           cpid = fork();
           if (cpid == -1) { perror("fork"); exit(EXIT_FAILURE); }
 
           if (cpid == 0) {    /* Child reads from pipe */
               close(pfd[1]);          /* Close unused write end */
 
               while (read(pfd[0], &buf, 1) > 0)
                   write(STDOUT_FILENO, &buf, 1);
 
               write(STDOUT_FILENO, "\n", 1);
               close(pfd[0]);
               _exit(EXIT_SUCCESS);
 
           } else {            /* Parent writes argv[1] to pipe */
               close(pfd[0]);          /* Close unused read end */
               write(pfd[1], argv[1], strlen(argv[1]));
               close(pfd[1]);          /* Reader will see EOF */
               wait(NULL);             /* Wait for child */
               exit(EXIT_SUCCESS);
           }
       }

父进程的 write你想发什么就发什么，子进程的read，读出来的东西，按你自己定的协议解析并执行就可以了