2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
202 lines
5.3 KiB
Groff
202 lines
5.3 KiB
Groff
.\" $NetBSD: setbuf.3,v 1.13 2003/08/07 16:43:31 agc Exp $
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.\"
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.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the American National Standards Committee X3, on Information
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.\" Processing Systems.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)setbuf.3 8.1 (Berkeley) 6/4/93
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.\"
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.Dd June 4, 1993
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.Dt SETBUF 3
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.Os
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.Sh NAME
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.Nm setbuf ,
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.Nm setbuffer ,
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.Nm setlinebuf ,
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.Nm setvbuf
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.Nd stream buffering operations
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In stdio.h
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.Ft void
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.Fn setbuf "FILE * restrict stream" "char * restrict buf"
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.Ft void
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.Fn setbuffer "FILE *stream" "char *buf" "size_t size"
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.Ft int
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.Fn setlinebuf "FILE *stream"
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.Ft int
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.Fn setvbuf "FILE * restrict stream" "char * restrict buf" "int mode" "size_t size"
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.Sh DESCRIPTION
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The three types of buffering available are unbuffered, block buffered,
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and line buffered.
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When an output stream is unbuffered, information appears on the
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destination file or terminal as soon as written;
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when it is block buffered many characters are saved up and written as a block;
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when it is line buffered characters are saved up until a newline is
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output or input is read from any stream attached to a terminal device
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(typically stdin).
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The function
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.Xr fflush 3
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may be used to force the block out early.
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(See
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.Xr fclose 3 . )
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.Pp
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Normally all files are block buffered.
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When the first
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.Tn I/O
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operation occurs on a file,
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.Xr malloc 3
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is called,
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and an optimally-sized buffer is obtained.
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If a stream refers to a terminal
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(as
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.Em stdout
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normally does) it is line buffered.
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The standard error stream
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.Em stderr
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is initially unbuffered.
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.Pp
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The
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.Fn setvbuf
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function
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may be used to alter the buffering behavior of a stream.
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The
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.Fa mode
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parameter must be one of the following three macros:
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.Bl -tag -width _IOFBF -offset indent
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.It Dv _IONBF
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unbuffered
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.It Dv _IOLBF
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line buffered
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.It Dv _IOFBF
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fully buffered
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.El
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.Pp
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The
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.Fa size
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parameter may be given as zero
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to obtain deferred optimal-size buffer allocation as usual.
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If it is not zero,
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then except for unbuffered files, the
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.Fa buf
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argument should point to a buffer at least
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.Fa size
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bytes long;
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this buffer will be used instead of the current buffer.
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(If the
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.Fa size
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argument
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is not zero but
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.Fa buf
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is
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.Dv NULL ,
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a buffer of the given size will be allocated immediately,
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and released on close.
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This is an extension to ANSI C;
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portable code should use a size of 0 with any
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.Dv NULL
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buffer.)
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.Pp
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The
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.Fn setvbuf
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function may be used at any time,
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but may have peculiar side effects
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(such as discarding input or flushing output)
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if the stream is ``active''.
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Portable applications should call it only once on any given stream,
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and before any
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.Tn I/O
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is performed.
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.Pp
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The other three calls are, in effect, simply aliases for calls to
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.Fn setvbuf .
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Except for the lack of a return value, the
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.Fn setbuf
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function is exactly equivalent to the call
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.Pp
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.Dl "setvbuf(stream, buf, buf ? _IOFBF : _IONBF, BUFSIZ);"
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.Pp
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The
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.Fn setbuffer
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function
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is the same, except that the size of the buffer is up to the caller,
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rather than being determined by the default
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.Dv BUFSIZ .
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The
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.Fn setlinebuf
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function
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is exactly equivalent to the call:
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.Pp
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.Dl "setvbuf(stream, (char *)NULL, _IOLBF, 0);"
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.Sh RETURN VALUES
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The
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.Fn setvbuf
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function returns 0 on success, or
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.Dv EOF
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if the request cannot be honored
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(note that the stream is still functional in this case).
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.Pp
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The
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.Fn setlinebuf
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function returns what the equivalent
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.Fn setvbuf
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would have returned.
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.Sh SEE ALSO
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.Xr fclose 3 ,
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.Xr fopen 3 ,
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.Xr fread 3 ,
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.Xr malloc 3 ,
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.Xr printf 3 ,
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.Xr puts 3
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.Sh STANDARDS
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The
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.Fn setbuf
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and
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.Fn setvbuf
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functions
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conform to
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.St -ansiC .
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.Sh BUGS
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The
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.Fn setbuffer
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and
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.Fn setlinebuf
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functions are not portable to versions of
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.Bx
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before
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.Bx 4.2 .
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On
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.Bx 4.2
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and
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.Bx 4.3
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systems,
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.Fn setbuf
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always uses a suboptimal buffer size and should be avoided.
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