fileno - obtain file descriptor of a stdio stream
Standard C library (
libc,
-lc)
#include <stdio.h>
int fileno(FILE *stream);
fileno():
_POSIX_C_SOURCE
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).
On success,
fileno() returns the file descriptor associated with
stream. On failure, -1 is returned and
errno is set to indicate
the error.
- EBADF
-
stream is not associated with a file.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
fileno () |
Thread safety |
MT-Safe |
The function
fileno() conforms to POSIX.1-2001 and POSIX.1-2008.
open(2),
fdopen(3),
stdio(3),
unlocked_stdio(3)