1SETVBUF(P)                 POSIX Programmer's Manual                SETVBUF(P)
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NAME

6       setvbuf - assign buffering to a stream
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SYNOPSIS

9       #include <stdio.h>
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11       int setvbuf(FILE *restrict stream, char *restrict buf, int type,
12              size_t size);
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DESCRIPTION

16       The  setvbuf()  function  may  be  used  after the stream pointed to by
17       stream is associated with an open file but before any  other  operation
18       (other  than  an  unsuccessful  call  to setvbuf()) is performed on the
19       stream. The argument type determines how stream shall be  buffered,  as
20       follows:
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22        * {_IOFBF} shall cause input/output to be fully buffered.
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24        * {_IOLBF} shall cause input/output to be line buffered.
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26        * {_IONBF} shall cause input/output to be unbuffered.
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28       If  buf  is  not  a  null  pointer,  the array it points to may be used
29       instead of a buffer allocated by setvbuf() and the argument size speci‐
30       fies the size of the array; otherwise, size may determine the size of a
31       buffer allocated by the setvbuf() function. The contents of  the  array
32       at any time are unspecified.
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34       For information about streams, see Standard I/O Streams .
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RETURN VALUE

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

43       The setvbuf() function may fail if:
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45       EBADF  The file descriptor underlying stream is not valid.
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48       The following sections are informative.
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EXAMPLES

51       None.
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APPLICATION USAGE

54       A common source of error is allocating buffer space as  an  "automatic"
55       variable  in  a code block, and then failing to close the stream in the
56       same block.
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58       With setvbuf(), allocating a buffer of size bytes does not  necessarily
59       imply that all of size bytes are used for the buffer area.
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61       Applications  should  note  that many implementations only provide line
62       buffering on input from terminal devices.
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RATIONALE

65       None.
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FUTURE DIRECTIONS

68       None.
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SEE ALSO

71       Standard I/O Streams , fopen() , setbuf() , the Base Definitions volume
72       of IEEE Std 1003.1-2001, <stdio.h>
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75       Portions  of  this text are reprinted and reproduced in electronic form
76       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
77       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
78       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
79       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
80       event of any discrepancy between this version and the original IEEE and
81       The  Open Group Standard, the original IEEE and The Open Group Standard
82       is the referee document. The original Standard can be  obtained  online
83       at http://www.opengroup.org/unix/online.html .
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87IEEE/The Open Group                  2003                           SETVBUF(P)
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