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


NAME
       stderr, stdin, stdout — standard I/O streams


SYNOPSIS
       #include <stdio.h>

       extern FILE *stderr, *stdin, *stdout;


DESCRIPTION
       The  functionality  described  on  this  reference  page is aligned with the ISO C standard. Any conflict
       between the requirements described  here  and  the  ISO C  standard  is  unintentional.  This  volume  of
       POSIX.1‐2017 defers to the ISO C standard.

       A  file  with  associated  buffering is called a stream and is declared to be a pointer to a defined type
       FILE.  The fopen() function shall create certain descriptive data for a stream and return  a  pointer  to
       designate  the  stream  in all further transactions. Normally, there are three open streams with constant
       pointers declared in the <stdio.h> header and associated with the standard open files.

       At program start-up, three streams shall be predefined and need not be opened explicitly: standard  input
       (for  reading  conventional input), standard output (for writing conventional output), and standard error
       (for writing diagnostic output). When opened, the standard  error  stream  is  not  fully  buffered;  the
       standard input and standard output streams are fully buffered if and only if the stream can be determined
       not to refer to an interactive device.

       The following symbolic values in <unistd.h> define the file descriptors that shall be associated with the
       C-language stdin, stdout, and stderr when the application is started:

       STDIN_FILENO  Standard input value, stdin.  Its value is 0.

       STDOUT_FILENO Standard output value, stdout.  Its value is 1.

       STDERR_FILENO Standard error value, stderr.  Its value is 2.

       The stderr stream is expected to be open for reading and writing.


RETURN VALUE
       None.


ERRORS
       No errors are defined.

       The following sections are informative.


EXAMPLES
       None.


APPLICATION USAGE
       None.


RATIONALE
       None.


FUTURE DIRECTIONS
       None.


SEE ALSO
       fclose(),  feof(),  ferror(),  fileno(),  fopen(), fprintf(), fread(), fscanf(), fseek(), getc(), gets(),
       popen(), putc(), puts(), read(), setbuf(), setvbuf(), tmpfile(), ungetc(), vfprintf()

       The Base Definitions volume of POSIX.1‐2017, <stdio.h>, <unistd.h>


COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical  and  Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee  document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .