NAME
fileno() — map stream pointer to file descriptor
SYNOPSIS
#include <stdio.h>
int fileno(FILE *stream);
Obsolescent Interfaces
int fileno_unlocked(FILE *stream);
DESCRIPTION
fileno()
returns the integer file descriptor associated with the named
stream;
see
open(2).
The following symbolic values in
<unistd.h>
define the file descriptors associated with
stdin,
stdout,
and
stderr
when a program is started :
- STDIN_FILENO
Value of zero for standard input,
stdin.
- STDOUT_FILENO
Value of 1 for standard output,
stdout.
- STDERR_FILENO
Value of 2 for standard error,
stderr.
Obsolescent Interfaces
fileno_unlocked()
map stream pointer to file descriptor
APPLICATION USAGE
fileno()
is thread-safe. It is not async-cancel-safe.
fileno_unlocked()
is an obsolescent interface supported only for compatibility with
existing DCE applications. New multithreaded applications should use
fileno().
RETURN VALUE
Upon error,
fileno() and fileno_unlocked()
return -1.
STANDARDS CONFORMANCE
fileno(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1
