mirror of https://github.com/mkerrisk/man-pages
68 lines
2.1 KiB
Plaintext
68 lines
2.1 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "FILENO" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" fileno
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.SH NAME
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fileno \- map a stream pointer to a file descriptor
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.SH SYNOPSIS
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.LP
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\fB#include <stdio.h>
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.br
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.sp
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int fileno(FILE *\fP\fIstream\fP\fB); \fP
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\fB
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fIfileno\fP() function shall return the integer file descriptor
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associated with the stream pointed to by
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\fIstream\fP.
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.SH RETURN VALUE
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.LP
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Upon successful completion, \fIfileno\fP() shall return the integer
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value of the file descriptor associated with \fIstream\fP.
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Otherwise, the value -1 shall be returned and \fIerrno\fP set to indicate
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the error.
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.SH ERRORS
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.LP
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The \fIfileno\fP() function may fail if:
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.TP 7
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.B EBADF
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The \fIstream\fP argument is not a valid stream.
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.sp
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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None.
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.SH APPLICATION USAGE
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.LP
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None.
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.SH RATIONALE
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.LP
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Without some specification of which file descriptors are associated
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with these streams, it is impossible for an application to
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set up the streams for another application it starts with \fIfork\fP()
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and \fIexec\fP. In particular, it would not be possible to write a
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portable version of the \fIsh\fP command interpreter (although there
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may be other constraints that would prevent that
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portability).
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fIInteraction of File Descriptors and Standard I/O Streams\fP , \fIfdopen\fP()
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, \fIfopen\fP() , \fIstdin\fP() , the Base
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Definitions volume of IEEE\ Std\ 1003.1-2001, \fI<stdio.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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