Section: POSIX Programmer's Manual (0P)
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
--- format of directory entries
The internal format of directories is unspecified.
header shall define the following type:
A type representing a directory stream. The
type may be an incomplete type.
It shall also define the structure
which shall include the following members:
ino_t d_ino File serial number.
char d_name Filename string of entry.
header shall define the
type as described in
is of unspecified size, but shall contain a filename of at most
bytes followed by a terminating null byte.
The following shall be declared as functions and may also be defined as
macros. Function prototypes shall be provided.
int alphasort(const struct dirent **, const struct dirent **);
int closedir(DIR *);
int dirfd(DIR *);
DIR *opendir(const char *);
struct dirent *readdir(DIR *);
int readdir_r(DIR *restrict, struct dirent *restrict,
struct dirent **restrict);
void rewinddir(DIR *);
int scandir(const char *, struct dirent ***,
int (*)(const struct dirent *),
int (*)(const struct dirent **,
const struct dirent **));
void seekdir(DIR *, long);
long telldir(DIR *);
The following sections are informative.
Information similar to that in the
header is contained in a file
in 4.2 BSD and 4.3 BSD. The equivalent in these implementations of
from this volume of POSIX.1-2017 is
The filename was changed because the name
was also used in earlier implementations to refer to definitions
related to the older access method; this produced name conflicts. The
name of the structure was changed because this volume of POSIX.1-2017 does not completely
define what is in the structure, so it could be different on some
The name of an array of
of an unspecified size should not be used as an lvalue. Use of:
is incorrect; use:
The array of
is not a fixed size. Implementations may need to declare
with an array size for
of 1, but the actual number of bytes provided matches (or only slightly
exceeds) the length of the filename string.
The System Interfaces volume of POSIX.1-2017,
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
Any typographical or formatting errors that appear
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to have been introduced during the conversion of the source files to
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