stdin(3p) — Linux manual page

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

       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(3p), feof(3p), ferror(3p), fileno(3p), fopen(3p),
       fprintf(3p), fread(3p), fscanf(3p), fseek(3p), getc(3p),
       gets(3p), popen(3p), putc(3p), puts(3p), read(3p), setbuf(3p),
       setvbuf(3p), tmpfile(3p), ungetc(3p), vfprintf(3p)

       The Base Definitions volume of POSIX.1‐2017, stdio.h(0p),
       unistd.h(0p)

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 .

IEEE/The Open Group               2017                         STDIN(3P)

Pages that refer to this page: stdio.h(0p), assert(3p), fileno(3p)

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