#include "apue.h"#include <fcntl.h>intmain(int argc, char *argv[]){	int		val;	if (argc != 2)		err_quit("usage: a.out <descriptor#>");	if ((val = fcntl(atoi(argv[1]), F_GETFL, 0)) < 0)		err_sys("fcntl error for fd %d", atoi(argv[1]));	switch (val & O_ACCMODE) {	case O_RDONLY:		printf("read only");		break;	case O_WRONLY:		printf("write only");		break;	case O_RDWR:		printf("read write");		break;	default:		err_dump("unknown access mode");	}	if (val & O_APPEND)		printf(", append");	if (val & O_NONBLOCK)		printf(", nonblocking");#if defined(O_SYNC)	if (val & O_SYNC)		printf(", synchronous writes");#endif#if !defined(_POSIX_C_SOURCE) && defined(O_FSYNC)	if (val & O_FSYNC)		printf(", synchronous writes");#endif	putchar('\n');	exit(0);}