DragonFly On-Line Manual Pages
DIR(5) DragonFly File Formats Manual DIR(5)
dir, dirent -- directory file format
Directories provide a convenient hierarchical method of grouping files
while obscuring the underlying details of the storage medium. A direc-
tory 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 directo-
ries 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(2) and mount(8).)
The directory entry format is defined in <sys/dirent.h>. This file
should not be included directly by applications.
A dir file format appeared in Version 7 AT&T UNIX.
The usage of the member d_type of struct dirent is unportable as it is
DragonFly/FreeBSD-specific. It also may fail on certain filesystems, for
example the cd9660 filesystem.
DragonFly 4.9 March 5, 2005 DragonFly 4.9