file stat

stat是linux下获取文件状态的一个命令，同时也可以做为函数来获取文件状态。

 int stat(const char *restrict path, struct stat *restrict buf);

int file_stat()
{
	struct stat stat1;
	int ret = -1;
	int file_count = 0;
	DIR *dir1 = NULL;
	struct dirent * dirent1 = NULL;
	memset(&stat1, 0, sizeof(stat1));
	ret = stat(FILENAME, &stat1); //获取stat结构体状态
	if(ret < 0)
	{
		perror("stat");
		return -1;
	}
	if ((stat1.st_mode & S_IFMT) == S_IFREG) //判断是否为文件
	{
	   /* Handle regular file */
		printf("%s is a file.\n", FILENAME);
	}
	if(S_ISREG(stat1.st_mode))        //判断是否为文件的另一种写法
	{
		printf("%s is a file.\n", FILENAME);
	}

	printf("file size=%lu, ino=%lu, uid=%u, mode=%d\n", stat1.st_size, stat1.st_ino, stat1.st_uid, stat1.st_mode);
	
	if(access(FILENAME, F_OK) == 0)  //判断文件是否存在
	{
		printf("F_OK\n");
	}
	if(access(FILENAME, W_OK) == 0)  //是否有写权限
	{
		printf("W_OK\n");
	}

	if(chmod(FILENAME, S_IWOTH) == 0)   //赋予other 写权限，同时其他组的权限也清空了
	{
		printf("chmod S_IWOTH success.\n");
	}

	dir1 = opendir("src");  //打开一个目录
	if(dir1 == NULL)
	{
		perror("opendir");
		return -1;
	}
	dirent1 = readdir(dir1);
	while(dirent1 != NULL)   //遍历出所有普通文件
	{
		if (dirent1->d_type == DT_REG) //DT_REG 判断是否为普通文件.
		{
			file_count++;
			printf("This is a regular file,file name =%s\n", dirent1->d_name); //DT_DIR      This is a directory.
		}
		dirent1 = readdir(dir1);
	}
	printf("file_count=%d\n", file_count);
	return 0;
}

stat结构体

           struct stat {
               dev_t     st_dev;         /* ID of device containing file */
               ino_t     st_ino;         /* inode number */
               mode_t    st_mode;        /* protection */
               nlink_t   st_nlink;       /* number of hard links */
               uid_t     st_uid;         /* user ID of owner */
               gid_t     st_gid;         /* group ID of owner */
               dev_t     st_rdev;        /* device ID (if special file) */
               off_t     st_size;        /* total size, in bytes */
               blksize_t st_blksize;     /* blocksize for filesystem I/O */
               blkcnt_t  st_blocks;      /* number of 512B blocks allocated */

               /* Since Linux 2.6, the kernel supports nanosecond
                  precision for the following timestamp fields.
                  For the details before Linux 2.6, see NOTES. */

               struct timespec st_atim;  /* time of last access */
               struct timespec st_mtim;  /* time of last modification */
               struct timespec st_ctim;  /* time of last status change */

           #define st_atime st_atim.tv_sec      /* Backward compatibility */
           #define st_mtime st_mtim.tv_sec
           #define st_ctime st_ctim.tv_sec
           };