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 (con-
       sult 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 associ-
       ated 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 out-
       put). 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   Definitions   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, Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                     STDIN(3P)