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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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fileno(3) Library Functions Manual fileno(3)
fileno - obtain file descriptor of a stdio stream
Standard C library (libc, -lc)
#include <stdio.h>
int fileno(FILE *stream);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
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 │
└─────────────────────────────────────┴───────────────┴─────────┘
POSIX.1-2008.
POSIX.1-2001.
open(2), fdopen(3), stdio(3), unlocked_stdio(3)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
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⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
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Linux man-pages 6.9.1 2024-05-02 fileno(3)
Pages that refer to this page: fsync(2), fclose(3), ferror(3), fflush(3), fmemopen(3), fopen(3), open_memstream(3), pcap_file(3pcap), stdio(3)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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