projects / thirdparty / man-pages.git / blame
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1 | .\" Copyright (c) 1990, 1991 The Regents of the University of California. |
| 2 | .\" and Copyright (C) 2021 Michael Kerrisk <mtk.manpages@gmail.com> | |
| 3 | .\" All rights reserved. | |
| 4 | .\" | |
| 5 | .\" This code is derived from software contributed to Berkeley by | |
| 6 | .\" Chris Torek and the American National Standards Committee X3, | |
| 7 | .\" on Information Processing Systems. | |
| 8 | .\" | |
| 47009d5e | 9 | .\" SPDX-License-Identifier: BSD-4-Clause-UC |
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10 | .\" |
| 11 | .\" Converted for Linux, Mon Nov 29 14:24:40 1993, faith@cs.unc.edu | |
| 12 | .\" Added remark on EBADF for fileno, aeb, 2001-03-22 | |
| 13 | .\" | |
| 4c1c5274 | 14 | .TH fileno 3 (date) "Linux man-pages (unreleased)" |
| acd8a0e3 MK |
15 | .SH NAME |
| 16 | fileno \- obtain file descriptor of a stdio stream | |
| cfba38f4 AC |
17 | .SH LIBRARY |
| 18 | Standard C library | |
| 19 | .RI ( libc ", " \-lc ) | |
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20 | .SH SYNOPSIS |
| 21 | .nf | |
| 22 | .B #include <stdio.h> | |
| 23 | .PP | |
| 24 | .BI "int fileno(FILE *" stream ); | |
| 25 | .fi | |
| 26 | .PP | |
| 27 | .RS -4 | |
| 28 | Feature Test Macro Requirements for glibc (see | |
| 29 | .BR feature_test_macros (7)): | |
| 30 | .RE | |
| 31 | .PP | |
| 32 | .BR fileno (): | |
| 33 | .nf | |
| 34 | _POSIX_C_SOURCE | |
| 35 | .fi | |
| 36 | .SH DESCRIPTION | |
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37 | The function |
| 38 | .BR fileno () | |
| 39 | examines the argument | |
| 40 | .I stream | |
| 41 | and returns the integer file descriptor used to implement this stream. | |
| 42 | The file descriptor is still owned by | |
| 43 | .I stream | |
| 44 | and will be closed when | |
| 45 | .BR fclose (3) | |
| 46 | is called. | |
| 47 | Duplicate the file descriptor with | |
| 48 | .BR dup (2) | |
| 49 | before passing it to code that might close it. | |
| 50 | .PP | |
| 51 | For the nonlocking counterpart, see | |
| 52 | .BR unlocked_stdio (3). | |
| 53 | .SH RETURN VALUE | |
| 54 | On success, | |
| 55 | .BR fileno () | |
| 56 | returns the file descriptor associated with | |
| 57 | .IR stream . | |
| 58 | On failure, \-1 is returned and | |
| 59 | .I errno | |
| 60 | is set to indicate the error. | |
| 61 | .SH ERRORS | |
| 62 | .TP | |
| 63 | .B EBADF | |
| 64 | .I stream | |
| 65 | is not associated with a file. | |
| 66 | .SH ATTRIBUTES | |
| 67 | For an explanation of the terms used in this section, see | |
| 68 | .BR attributes (7). | |
| 69 | .ad l | |
| 70 | .nh | |
| 71 | .TS | |
| 72 | allbox; | |
| 73 | lbx lb lb | |
| 74 | l l l. | |
| 75 | Interface Attribute Value | |
| 76 | T{ | |
| 77 | .BR fileno () | |
| 78 | T} Thread safety MT-Safe | |
| 79 | .TE | |
| 80 | .hy | |
| 81 | .ad | |
| 82 | .sp 1 | |
| 3113c7f3 | 83 | .SH STANDARDS |
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84 | The function |
| 85 | .BR fileno () | |
| 86 | conforms to POSIX.1-2001 and POSIX.1-2008. | |
| 87 | .SH SEE ALSO | |
| 88 | .BR open (2), | |
| 89 | .BR fdopen (3), | |
| 90 | .BR stdio (3), | |
| 91 | .BR unlocked_stdio (3) |