1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 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 $ 31.\" 32.Dd March 5, 2005 33.Dt DIR 5 34.Os 35.Sh NAME 36.Nm dir , 37.Nm dirent 38.Nd directory file format 39.Sh SYNOPSIS 40.In dirent.h 41.Sh DESCRIPTION 42Directories provide a convenient hierarchical method of grouping 43files while obscuring the underlying details of the storage medium. 44A directory file is differentiated from a plain file 45by a flag in its 46.Xr inode 5 47entry. 48It consists of records (directory entries) each of which contains 49information about a file and a pointer to the file itself. 50Directory entries may contain other directories 51as well as plain files; such nested directories are referred to as 52subdirectories. 53A hierarchy of directories and files is formed in this manner 54and is called a file system (or referred to as a file system tree). 55.\" An entry in this tree, 56.\" nested or not nested, 57.\" is a pathname. 58.Pp 59Each directory file contains two special directory entries; one is a pointer 60to the directory itself 61called dot 62.Ql .\& 63and the other a pointer to its parent directory called dot-dot 64.Ql \&.. . 65Dot and dot-dot 66are valid pathnames, however, 67the system root directory 68.Ql / , 69has no parent and dot-dot points to itself like dot. 70.Pp 71File system nodes are ordinary directory files on which has 72been grafted a file system object, such as a physical disk or a 73partitioned area of such a disk. 74(See 75.Xr mount 2 76and 77.Xr mount 8 . ) 78.Pp 79The directory entry format is defined in 80.In sys/dirent.h . 81This file should not be included directly by applications. 82.Sh SEE ALSO 83.Xr fs 5 , 84.Xr inode 5 85.Sh HISTORY 86A 87.Nm 88file format appeared in 89.At v7 . 90.Sh BUGS 91The usage of the member d_type of struct dirent is unportable as it is 92.Dx Ns / Ns Fx Ns -specific . 93It also may fail on certain filesystems, for example the cd9660 filesystem. 94