---
name: "dir"
section: "5"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["freebsd", "openbsd", "macos"]
url: "https://new.carta.tech/dir/5"
---

# dir(5)

directory file format

## NAME

**dir**, **dirent** – directory file format

## SYNOPSIS

**#include \<dirent.h\>**

## DESCRIPTION

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)](/inode/5.md) 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)](/mount/8.md)).

The directory entry format is defined in the file ⟨dirent.h⟩:

```
/*
 * A directory entry has a struct dirent at the front of it, containing
 * its inode number, the length of the entry, and the length of the name
 * contained in the entry.  These are followed by the name padded to some
 * alignment (currently 8 bytes) with NUL bytes.  All names are guaranteed
 * NUL terminated.  The maximum length of a name in a directory is MAXNAMLEN.
 */
struct dirent {
	ino_t		d_fileno;	/* file number of entry */
	off_t		d_off;		/* offset of next entry */
	u_int16_t	d_reclen;	/* length of this record */
	u_int8_t	d_type;		/* file type, see below */
	u_int8_t	d_namlen;	/* length of string in d_name */
#define MAXNAMLEN       255
	char    d_name[MAXNAMLEN + 1];  /* maximum name length */
};
#define	d_ino		d_fileno	/* backward compatibility */
/*
 * File types
 */
#define DT_UNKNOWN	0
#define DT_FIFO		1
#define DT_CHR		2
#define DT_DIR		4
#define DT_BLK		6
#define DT_REG		8
#define DT_LNK		10
#define DT_SOCK		12
```

## SEE ALSO

[getdents(2)](/getdents/2.md), [fs(5)](/fs/5.md), [inode(5)](/inode/5.md)

## HISTORY

A **dir** file format appeared in Version 1 AT&T UNIX. A predecessor *struct* *direct* first appeared in Version 7 AT&T UNIX. The *dirent* structure first appeared in 4.3BSD-Reno. The *d\_off* member was added in OpenBSD 5.5.