#include "apue.h"static int	pfd1[2], pfd2[2];voidTELL_WAIT(void){	if (pipe(pfd1) < 0 || pipe(pfd2) < 0)		err_sys("pipe error");}voidTELL_PARENT(pid_t pid){	if (write(pfd2[1], "c", 1) != 1)		err_sys("write error");}voidWAIT_PARENT(void){	char	c;	if (read(pfd1[0], &c, 1) != 1)		err_sys("read error");	if (c != 'p')		err_quit("WAIT_PARENT: incorrect data");}voidTELL_CHILD(pid_t pid){	if (write(pfd1[1], "p", 1) != 1)		err_sys("write error");}voidWAIT_CHILD(void){	char	c;	if (read(pfd2[0], &c, 1) != 1)		err_sys("read error");	if (c != 'c')		err_quit("WAIT_CHILD: incorrect data");}