dirfd - get directory stream file descriptor
int dirfd(DIR *dirp);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
/* Since glibc 2.10: */
_POSIX_C_SOURCE >= 200809L
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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.
On success, a nonnegative file descriptor is returned. On error, -1 is returned,
and errno is set to indicate the cause of the error.
POSIX.1-2008 specifies two errors, neither of which is returned by the current
For an explanation of the terms used in this section, see attributes(7).
- dirp does not refer to a valid directory stream.
- The implementation does not support the association of a file descriptor
with a directory.
POSIX.1-2008. This function was a BSD extension, present in 4.3BSD-Reno, not in
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