fileno
Section: C Library Functions (3)
Updated: 2022-12-15
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NAME
fileno - obtain file descriptor of a stdio stream
LIBRARY
Standard C library
(libc, -lc)
SYNOPSIS
#include <stdio.h>
int fileno(FILE *stream);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
fileno():
_POSIX_C_SOURCE
DESCRIPTION
The function
fileno()
examines the argument
stream
and returns the integer file descriptor used to implement this stream.
The file descriptor is still owned by
stream
and will be closed when
fclose(3)
is called.
Duplicate the file descriptor with
dup(2)
before passing it to code that might close it.
For the nonlocking counterpart, see
unlocked_stdio(3).
RETURN VALUE
On success,
fileno()
returns the file descriptor associated with
stream.
On failure, -1 is returned and
errno
is set to indicate the error.
ERRORS
- EBADF
-
stream
is not associated with a file.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
|
fileno()
| Thread safety | MT-Safe
|
STANDARDS
The function
fileno()
conforms to POSIX.1-2001 and POSIX.1-2008.
SEE ALSO
open(2),
fdopen(3),
stdio(3),
unlocked_stdio(3)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- STANDARDS
-
- SEE ALSO
-
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