#include "apue.h"intmain(void){	struct stat		statbuf;	/* turn on set-group-ID and turn off group-execute */	if (stat("foo", &statbuf) < 0)		err_sys("stat error for foo");	if (chmod("foo", (statbuf.st_mode & ~S_IXGRP) | S_ISGID) < 0)		err_sys("chmod error for foo");	/* set absolute mode to "rw-r--r--" */	if (chmod("bar", S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) < 0)		err_sys("chmod error for bar");	exit(0);}