'\" t
.\" Copyright, The contributors to the Linux man-pages project
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH opendir 3 2025-05-06 "Linux man-pages 6.14"
.SH NAME
opendir, fdopendir \- open a directory
.SH LIBRARY
Standard C library
.RI ( libc ,\~ \-lc )
.SH SYNOPSIS
.nf
.B #include <sys/types.h>
.B #include <dirent.h>
.P
.BI "DIR *opendir(const char *" name );
.BI "DIR *fdopendir(int " fd );
.fi
.P
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.P
.BR fdopendir ():
.nf
    Since glibc 2.10:
        _POSIX_C_SOURCE >= 200809L
    Before glibc 2.10:
        _GNU_SOURCE
.fi
.SH DESCRIPTION
The
.BR opendir ()
function opens a directory stream corresponding to the
directory
.IR name ,
and returns a pointer to the directory stream.
The stream is positioned at the first entry in the directory.
.P
The
.BR fdopendir ()
function
is like
.BR opendir (),
but returns a directory stream for the directory referred
to by the open file descriptor
.IR fd .
After a successful call to
.BR fdopendir (),
.I fd
is used internally by the implementation,
and should not otherwise be used by the application.
.SH RETURN VALUE
The
.BR opendir ()
and
.BR fdopendir ()
functions return a pointer to the directory stream.
On error, NULL is returned, and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EACCES
Permission denied.
.TP
.B EBADF
.I fd
is not a valid file descriptor opened for reading.
.TP
.B EMFILE
The per-process limit on the number of open file descriptors has been reached.
.TP
.B ENFILE
The system-wide limit on the total number of open files has been reached.
.TP
.B ENOENT
Directory does not exist, or
.I name
is an empty string.
.TP
.B ENOMEM
Insufficient memory to complete the operation.
.TP
.B ENOTDIR
.I name
is not a directory.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.na
.nh
.BR opendir (),
.BR fdopendir ()
T}	Thread safety	MT-Safe
.TE
.SH STANDARDS
POSIX.1-2008.
.SH STANDARDS
.TP
.BR opendir ()
SVr4, 4.3BSD, POSIX.1-2001.
.TP
.BR fdopendir ()
POSIX.1-2008.
glibc 2.4.
.SH NOTES
Filename entries can be read from a directory stream using
.BR readdir (3).
.P
The underlying file descriptor of the directory stream can be obtained using
.BR dirfd (3).
.P
The
.BR opendir ()
function sets the close-on-exec flag for the file descriptor underlying the
.IR "DIR *" .
The
.BR fdopendir ()
function leaves the setting of the close-on-exec
flag unchanged for the file descriptor,
.IR fd .
POSIX.1-200x leaves it unspecified whether a successful call to
.BR fdopendir ()
will set the close-on-exec flag for the file descriptor,
.IR fd .
.SH SEE ALSO
.BR open (2),
.BR closedir (3),
.BR dirfd (3),
.BR readdir (3),
.BR rewinddir (3),
.BR scandir (3),
.BR seekdir (3),
.BR telldir (3)