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28 .\" @(#)dir.5 8.3 (Berkeley) 4/19/94
29 .\" $FreeBSD: src/share/man/man5/dir.5,v 1.12.2.5 2001/12/17 11:30:13 ru Exp $
30 .\" $DragonFly: src/share/man/man5/dir.5,v 1.7 2006/05/26 19:39:40 swildner Exp $
38 .Nd directory file format
42 Directories provide a convenient hierarchical method of grouping
43 files while obscuring the underlying details of the storage medium.
44 A directory file is differentiated from a plain file
48 It consists of records (directory entries) each of which contains
49 information about a file and a pointer to the file itself.
50 Directory entries may contain other directories
51 as well as plain files; such nested directories are referred to as
53 A hierarchy of directories and files is formed in this manner
54 and is called a file system (or referred to as a file system tree).
55 .\" An entry in this tree,
56 .\" nested or not nested,
59 Each directory file contains two special directory entries; one is a pointer
60 to the directory itself
63 and the other a pointer to its parent directory called dot-dot
66 are valid pathnames, however,
67 the system root directory
69 has no parent and dot-dot points to itself like dot.
71 File system nodes are ordinary directory files on which has
72 been grafted a file system object, such as a physical disk or a
73 partitioned area of such a disk.
79 The directory entry format is defined in
81 This file should not be included directly by applications.
88 file format appeared in
91 The usage of the member d_type of struct dirent is unportable as it is
92 .Dx Ns / Ns Fx Ns -specific .
93 It also may fail on certain filesystems, for example the cd9660 filesystem.