dirfd(3)		    Library Functions Manual			dirfd(3)

NAME
     dirfd - get directory stream file descriptor

LIBRARY
     Standard C library (libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <dirent.h>

     int dirfd(DIR *dirp);

 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

     dirfd():
	 /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200809L
	     || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION
     The function dirfd() returns the file descriptor associated with the direc-
     tory stream dirp.

     This  file	 descriptor  is the one used internally by the directory stream.
     As a result, it is useful only for functions which do not depend on or  al-
     ter the file position, such as fstat(2) and fchdir(2).  It will be automat-
     ically closed when closedir(3) is called.

RETURN VALUE
     On	 success, dirfd() returns a file descriptor (a nonnegative integer).  On
     error, -1 is returned, and errno is set to indicate the error.

ERRORS
     POSIX.1-2008 specifies two errors, neither of which is returned by the cur-
     rent implementation.

     EINVAL
	    dirp does not refer to a valid directory stream.

     ENOTSUP
	    The implementation does not support the association of  a  file  de-
	    scriptor with a directory.

ATTRIBUTES
     For  an  explanation  of the terms used in this section, see attributes(7).
     allbox; lbx lb lb l l l.  Interface Attribute Value T{ dirfd() T}	 Thread
     safety  MT-Safe

STANDARDS
     POSIX.1-2008.

HISTORY
     4.3BSD-Reno (not in 4.2BSD).

SEE ALSO
     open(2),  openat(2),  closedir(3),	 opendir(3),  readdir(3),  rewinddir(3),
     scandir(3), seekdir(3), telldir(3)

Linux man-pages 6.18		   2026-02-08				dirfd(3)