centos man page for setvbuf

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

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

NAME
       setvbuf - assign buffering to a stream

SYNOPSIS
       #include <stdio.h>

       int setvbuf(FILE *restrict stream, char *restrict buf, int type,
	      size_t size);

DESCRIPTION
       The setvbuf() function may be used after the stream pointed to by stream is associated with an open file but  before  any  other  operation
       (other  than  an  unsuccessful call to setvbuf()) is performed on the stream. The argument type determines how stream shall be buffered, as
       follows:

	* {_IOFBF} shall cause input/output to be fully buffered.

	* {_IOLBF} shall cause input/output to be line buffered.

	* {_IONBF} shall cause input/output to be unbuffered.

       If buf is not a null pointer, the array it points to may be used instead of a buffer allocated by setvbuf() and the argument size specifies
       the size of the array; otherwise, size may determine the size of a buffer allocated by the setvbuf() function. The contents of the array at
       any time are unspecified.

       For information about streams, see Standard I/O Streams .

RETURN VALUE
       Upon successful completion, setvbuf() shall return 0. Otherwise, it shall return a non-zero value if an invalid value is given for type	or
       if the request cannot be honored,  and may set errno to indicate the error.

ERRORS
       The setvbuf() function may fail if:

       EBADF  The file descriptor underlying stream is not valid.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       A common source of error is allocating buffer space as an "automatic" variable in a code block, and then failing to close the stream in the
       same block.

       With setvbuf(), allocating a buffer of size bytes does not necessarily imply that all of size bytes are used for the buffer area.

       Applications should note that many implementations only provide line buffering on input from terminal devices.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Standard I/O Streams, fopen(), setbuf(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- 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							       SETVBUF(3P)