linux--Basic article--dir dirent Stat

The dir struct under Linux is defined as

1 struct__dirstream2    {3     void*__fd;4     Char*__data;5     int__entry_data;6     Char*__ptr;7     int__entry_ptr;8 size_t __allocation;9 size_t __size;Ten __libc_lock_define (, __lock) One    }; Atypedefstruct__dirstream DIR;

The struct holds the directory-related information, such as opendir (const char *), and returns the type of Dir *;

The functions used in this structure are also:

1 struct dirent *readdir (DIR *dp); 2 void Rewinddir (DIR *dp); 3 int closedir (DIR *dp); 4 long telldir (DIR *dp); 5 void Seekdir (DIR *dp,long Loc);

When you get dir *, the Readdir (dir *) function gives you a pointer to the Dirent type Dirent structure not only saves directory information, but also holds specific information about a file

The dirent structure is defined as

1 structdirent2 {3  　　 LongD_ino;/*inode Number Index node*/4off_t D_off;/*offset to this dirent in the directory file*/5Unsigned ShortD_reclen;/*length of this d_name filename long*/6UnsignedCharD_type;/*The type of d_name file type*/7     CharD_name [name_max+1];/*File name (null-terminated) file name, maximum 255 characters*/8}

Through Dirent's d_name, use the following function

int stat (const char *file_name, struct stat *buf);

You can get more detailed information about a file, and you can implement the LS function in Linux.

The stat structure is defined as

1 structStat {2mode_t St_mode;//File access Permissions3ino_t St_ino;//Index Node Number4dev_t St_dev;//the device number used by the file5dev_t St_rdev;//Device number of the device file6nlink_t St_nlink;//number of hard connections to a file7uid_t St_uid;//owner user identification number8gid_t St_gid;//Group Identification Number9off_t st_size;//file capacity in bytesTentime_t St_atime;//the last time the file was accessed Onetime_t St_mtime;//the last time the file was modified Atime_t St_ctime;//The last time the file state was changed -blksize_t st_blksize;//The size of the disk block that contains the file -blkcnt_t st_blocks;//the disk block that the file occupies the};

Here is a simple implementation of LS (for advanced programming of the UNIX environment):

By: http://www.liweifan.com/2012/05/13/linux-system-function-files-operation/

linux--Basic article--dir dirent Stat