c - Fork a child process,runs permanently in the background and do work -

i want fork child process runs permanently in background, , parent prompt user enter line of text. display number of lines entered user in child process.

how it??

#include <stdio.h> #include <stdlib.h> #include <sys/types.h>  int main ( int argc, char *argv[] ) {      int i, pid, status;      pid = fork();       switch(pid){         case -1: printf("fork error");         break;         case 0: printf("in child pid %d\n", (int)getpid());         // print out number of lines on screen         while(1);         break;         default: printf("in parents pid %d\n", (int)getpid());         printf("\nplease enter somthing...\n");         // maybe counting here? , send on child?         wait(&status);         break;     } } 

#include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <unistd.h> #include <string.h>  void do_parent(); void do_child();  int fd[2] = { 0 };  int main ( int argc, char *argv[] ) {      int pid;       if (pipe(fd) < 0) {         fprintf(stderr, "error opening pipe\n");         exit(-1);      }      switch(pid = fork()) {         case -1:              fprintf(stderr, "fork error\n");             exit(-1);         case 0:              do_child();             fprintf(stderr, "child exited\n");             exit(0);         default:             do_parent(pid);             fprintf(stderr, "parent exited\n");             exit(0);      } }  void do_parent(int child_pid)  {      printf("parent pid: %d, child's pid: %d\n", getpid(), child_pid);     dup2(fd[0], 0);     char buf[256];     while(gets(buf) != null && strncmp(buf, "done", 4) != 0)         printf("parent received: %s\n", buf);     printf("nothing left child\n"); }  void do_child()  {     dup2(fd[1], 1);     (int = 0; < 100; i++)         printf("child iteration #%d\n", i);     printf("done\n");  }