1STDIN(3P)                  POSIX Programmer's Manual                 STDIN(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

13       stderr, stdin, stdout — standard I/O streams
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SYNOPSIS

16       #include <stdio.h>
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18       extern FILE *stderr, *stdin, *stdout;
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DESCRIPTION

21       The functionality described on this reference page is aligned with  the
22       ISO C  standard.  Any  conflict between the requirements described here
23       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2008
24       defers to the ISO C standard.
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26       A  file with associated buffering is called a stream and is declared to
27       be a pointer to a defined type FILE.  The fopen() function shall create
28       certain descriptive data for a stream and return a pointer to designate
29       the stream in all further transactions. Normally, there are three  open
30       streams  with  constant  pointers  declared in the <stdio.h> header and
31       associated with the standard open files.
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33       At program start-up, three streams shall be predefined and need not  be
34       opened  explicitly:  standard  input  (for reading conventional input),
35       standard output (for writing conventional output), and  standard  error
36       (for writing diagnostic output). When opened, the standard error stream
37       is not fully buffered; the standard input and standard  output  streams
38       are  fully  buffered if and only if the stream can be determined not to
39       refer to an interactive device.
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41       The following symbolic values in <unistd.h> define the file descriptors
42       that  shall be associated with the C-language stdin, stdout, and stderr
43       when the application is started:
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45       STDIN_FILENO  Standard input value, stdin.  Its value is 0.
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47       STDOUT_FILENO Standard output value, stdout.  Its value is 1.
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49       STDERR_FILENO Standard error value, stderr.  Its value is 2.
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51       The stderr stream is expected to be open for reading and writing.
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RETURN VALUE

54       None.
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ERRORS

57       No errors are defined.
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59       The following sections are informative.
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EXAMPLES

62       None.
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APPLICATION USAGE

65       None.
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RATIONALE

68       None.
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FUTURE DIRECTIONS

71       None.
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SEE ALSO

74       fclose(), feof(),  ferror(),  fileno(),  fopen(),  fprintf(),  fread(),
75       fscanf(),  fseek(),  getc(),  gets(),  popen(), putc(), puts(), read(),
76       setbuf(), setvbuf(), tmpfile(), ungetc(), vfprintf()
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78       The Base Definitions volume of POSIX.1‐2008, <stdio.h>, <unistd.h>
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81       Portions of this text are reprinted and reproduced in  electronic  form
82       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
83       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
84       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
85       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
86       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
87       event of any discrepancy between this version and the original IEEE and
88       The  Open Group Standard, the original IEEE and The Open Group Standard
89       is the referee document. The original Standard can be  obtained  online
90       at http://www.unix.org/online.html .
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92       Any  typographical  or  formatting  errors that appear in this page are
93       most likely to have been introduced during the conversion of the source
94       files  to  man page format. To report such errors, see https://www.ker‐
95       nel.org/doc/man-pages/reporting_bugs.html .
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99IEEE/The Open Group                  2013                            STDIN(3P)
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