#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>

int error_pipe(int pn)

{
   if ( pn < 0) perror("Error in fork()\n");
    return 126;
}

int main()
{
  int fd[2],status;
  pid_t p1,p2;
  char* ch1[]={"ls","-l",NULL};
  char* ch2[]={"grep","abc",NULL};
  pipe(fd);
  if ((p1 = fork())== 0)
  {
    dup2(fd[1],1);
    close(fd[0]);
    close(fd[1]);
    execvp(ch1[0],ch1);

   } // end if

  else  error_pipe(p1);

  if ((p2 = fork()) == 0)
  {
    dup2(fd[0], 0);
    close(fd[0]);
    close(fd[1]);
    execvp(ch2[0],ch2);
  }// end if

  else error_pipe(p2);

  close(fd[0]);
  close(fd[1]);

  waitpid(p1,NULL ,0);
  waitpid(p2, &status,0);

if (status != 0)
  {
    printf ("No such file ...\n");
  }
  return 0;
}