.\" Copyright (C) 2002 Andries Brouwer (aeb@cwi.nl)
.\"
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.TH DIRFD 3 2010-09-26 "Linux" "Linux Programmer's Manual"
.SH NAME
dirfd \- get directory stream file descriptor
.SH SYNOPSIS
.B #include <sys/types.h>
.br
.B #include <dirent.h>
.sp
.BI "int dirfd(DIR *" dirp );
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.BR dirfd ():
.br
.RS 4
.PD 0
.ad l
_BSD_SOURCE || _SVID_SOURCE
.br
|| /* Since glibc 2.10: */
.RS 4
(_POSIX_C_SOURCE\ >=\ 200809L || _XOPEN_SOURCE\ >=\ 700)
.RE
.PD
.RE
.ad
.SH DESCRIPTION
The function
.BR dirfd ()
returns the file descriptor associated with the directory stream
.IR dirp .
.LP
This descriptor is the one used internally by the directory stream.
As a result, it is only useful for functions which do not depend on
or alter the file position, such as
.BR fstat (2)
and
.BR fchdir (2).
It will be automatically closed when
.BR closedir (3)
is called.
.SH RETURN VALUE
On success, a nonnegative file descriptor is returned.
On error, \-1 is returned.
.SH ERRORS
POSIX.1-2008 specifies two errors,
neither of which is returned by the current
.\" glibc 2.8
implementation.
.TP
.B EINVAL
.I dirp
does not refer to a valid directory stream.
.TP
.B ENOTSUP
The implementation does not support the association of a file
descriptor with a directory.
.SH "CONFORMING TO"
POSIX.1-2008.
This function was a BSD extension, present in 4.3BSD-Reno, not in 4.2BSD.
.\" It is present in libc5 (since 5.1.2) and in glibc2.
.SH NOTES
The prototype for
.BR dirfd ()
is only available if
.B _BSD_SOURCE
or
.B _SVID_SOURCE
is defined.
.SH "SEE ALSO"
.BR open (2),
.BR closedir (3),
.BR opendir (3),
.BR readdir (3),
.BR rewinddir (3),
.BR scandir (3),
.BR seekdir (3),
.BR telldir (3)
.SH COLOPHON
This page is part of release 3.44 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.