dirfd(3) — Linux manual page

dirfd(3)                 Library Functions Manual                dirfd(3)

NAME         top

       dirfd - get directory stream file descriptor

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #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         top

       The function dirfd() returns the file descriptor associated with
       the directory 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 alter the file position, such as fstat(2) and
       fchdir(2).  It will be automatically closed when closedir(3) is
       called.

RETURN VALUE         top

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

ERRORS         top

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

       EINVAL dirp does not refer to a valid directory stream.

       ENOTSUP
              The implementation does not support the association of a
              file descriptor with a directory.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                            │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │ dirfd()                              │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS         top

       POSIX.1-2008.

HISTORY         top

       4.3BSD-Reno (not in 4.2BSD).

SEE ALSO         top

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

COLOPHON         top

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Linux man-pages 6.15            2025-05-17                       dirfd(3)

Pages that refer to this page: open(2),  opendir(3),  readdir(3)

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