|DIRENT(3)||Library Functions Manual||DIRENT(3)|
dirent — directory
Directories provide a convenient hierarchical method of grouping files while obscuring the underlying details of the storage medium. A directory file is differentiated from a plain file by a flag in its inode(5) entry. It consists of records (directory entries) each of which contains information about a file and a pointer to the file itself. Directory entries may contain other directories as well as plain files; such nested directories are referred to as subdirectories. A hierarchy of directories and files is formed in this manner and is called a file system (or referred to as a file system tree).
Each directory file contains two special directory entries; one is
a pointer to the directory itself called dot
.’ and the other a pointer to its
parent directory called dot-dot ‘
Dot and dot-dot are valid pathnames, however, the system root directory
/’, has no parent and dot-dot points
to itself like dot.
File system nodes are ordinary directory files on which has been grafted a file system object, such as a physical disk or a partitioned area of such a disk. (See mount(8).)
ino_t d_fileno; uint16_t d_reclen; uint16_t d_namlen; uint8_t d_type; char d_name[MAXNAMLEN + 1];
The following table lists the types available for d_type and the corresponding ones used in the struct stat (see stat(2)), respectively:
||-||unknown file type|
||UNIX domain socket|
||dummy “whiteout inode”|
DT_WHT type is internal to the
implementation and should not be seen in normal user applications. The
can be used to convert from struct dirent types to
struct stat types, and vice versa.
The IEEE Std 1003.1-2001 (“POSIX.1”) standard specifies only the fields d_ino and d_name. The remaining fields are available on many, but not all systems.
Furthermore, the standard leaves the size of
d_name as unspecified, mentioning only that the number
of bytes preceding the terminating NUL shall not exceed
NAME_MAX. Because of this, and because the
d_namlen field may not be present, a portable
application should determine the size of d_name by
using strlen(3) instead of
A dir structure appeared in Version 7 AT&T UNIX. The dirent structure appeared in NetBSD 1.3.
|May 16, 2010||NetBSD-7.0.1|