linux下如果open判断文件存在时，使用O_EXCL或O_TRUNC会返回失败，rtthread中的DFS的open判断文件存在时，使用使用O_EXCL或O_TRUNC会返回成功，确实有一定的差异！
#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <stdio.h>#include <stdlib.h>void main(){ int fd; //fd = open("./data.txt",O_RDWR|O_CREAT|O_TRUNC); fd = open("./data.txt",O_RDWR|O_CREAT|O_EXCL);/**如果文件存在，fd返回-1，否则返回1**/ if(fd == -1){ fd = open("./data.txt",O_RDWR|O_TRUNC); if(fd == -1){ printf("file is exiting ,trunc mode open file success!\r\n"); write(fd,"hello world!\r\n",sizeof("hello world!\r\n")); }else{ printf("file is exiting,open file failed!\r\n"); } }else{ printf("file is not exiting, open file success!\r\n"); write(fd,"hello world!\r\n",sizeof("hello world!\r\n")); }}
