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

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
       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(),  fread(),  fseek(),
       getc(), gets(), popen(), printf(),  putc(),  puts(),  read(),  scanf(),
       setbuf(),  setvbuf(),  tmpfile(), ungetc(), vprintf(), the Base Defini-
       tions volume of IEEE Std 1003.1-2001, <stdio.h>, <unistd.h>
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 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 .

IEEE/The Open Group                  2003                            STDIN(3P)